Key Lime Mousse Tart

Since we are well into Spring and Easter is almost upon us, I thought I should showcase a seasonal dessert!  Something light, refreshing, tangy and sweet all at the same time.  Maybe with a tropical nod.   Key Lime Mousse Tart!  The best part is that it can be served like a light, fluffy cloud of key lime mousse-ness OR a melty-frozen confectioned semifreddo. You choose.

Nilla wafers for the crust.

Living in South Florida, I’ve had my fair share of key lime pie and I love it!  But sometimes, I want to switch it up.  For this Key Lime Mousse Tart, my changes start with the crust.  Instead of graham — I used NILLA Wafers and flaked coconut.

Blending cookies and sugar in a food processor.

NILLA Wafers remind me of my childhood.  They were the one cookie that I could always coax my mother into buying.  She’d shake her head over anything creme filled, or chip-laden, but NILLA Wafers — she approved of.

Making the nilla wafer crust.

Back to the tart… To make the crust,  whiz the cookies in a food processor with a little sugar.

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Then add melted butter and sweetened flaked coconut to the cookie crumbs.

Mixing the butter, crumbs and coconut.

The crust comes together in about 5 minutes from start to finish.  Then just press the crust into a tart shell with a removable bottom and bake it for 8-10 minutes, until its golden brown and set.

baking the crust for the key lime tart.

I have to say, when I took this shell from the oven, I started to question my sanity.  Why do I struggle making pastry — when this type of mix and press pie shell is so easy.  Seriously – what have I been thinking?

Mixing key lime juice and condensed milk.

Ingredients For Key Lime Mousse Tart Filling:

  • Key Lime Juice
  • Sweetened Condensed Milk
  • Water
  • Gelatin
  • Heavy Cream
  • Sugar

The key lime mousse filling starts with sweetened condensed milk and key lime juice.  They sell key limes by the bag here in Florida, but if you can’t find them, look for bottled key lime juice or just use regular persian limes.

Stirring the key lime filling until combined.

There are no eggs in this recipe because you don’t bake the filling — and you don’t want to mess with that whole “raw egg” thing.  Besides, the key lime mousse filling is going to be folded into a whole lot of whipped cream!

Whipped cream is an ethereal thing, but it has a shelf life.  If you want your tart to hold up for a few days, I recommend stabilizing the whipped cream.  It sounds technical, but it’s pretty easy to do!  It starts with plain gelatin.  Bloom the gelatin for a few minutes with water, then nuke it in 10 second bursts until it dissolves.  Usually 2-3 nukes.  Then let it cool — but not “set”.

While the gelatin cools, whip the cream for a minute, and then very slowly start adding the sugar.  Check that the gelatin has cooled but is still pourable and add it to the cream.  Continue to beat until stiff peaks form.  Ta-da!  Stabilized whipped cream.  Reserve about 1 cup of whipped cream for garnish– just stick it in the fridge until you’re ready for it.

Fold the stabilized whipped cream into the custard.

Stir a little whipped cream into the custard to lighten it before folding in the rest.

Fill the baked crust with key lime mousse.

Spread the filling into the cooled tart shell.

Pipe rosettes of whipped cream on the tart.

Pipe the reserved whipped topping over the tart.

Garnish the key lime tart.

I like to garnish with thin half moons of key lime and toasted coconut.   Now here comes the tough part… Deciding what kind of tart you want… Light, fluffy mousse-like or a creamy, semi-frozen confection (also known as a semi-freddo)?

Serving the key lime mousse tart on a cake plate.

For the former,  refrigerate the tart for at least two hours.  If you prefer the latter,  freeze it for two hours!

When refrigerating the key lime mousse tart, you can expect a sweet, cloud-like filling — and I don’t know anyone who doesn’t like that.  The semifreddo version is incredible on a warm day. I served it at a holiday luncheon for the family and there wasn’t a scrap left.

If you go with the frozen tart — let it rest on the counter for 10 or 15 minutes before slicing.  It will still be firm, but not rock solid — and that’s what you’re looking for.

This tangy, sweet tart would be a perfect dessert for Easter or Mother’s Day.

More key lime recipes you’ll love:

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Key lime mousse tart on a cake plate.
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4.75 from 16 votes

Key Lime Mousse Tart

Whipped cream folded into a key lime filling and set in a Nilla wafer and coconut crust is a delicious spring or summer dessert!
Author: Lisa Lotts
Course Dessert
Cuisine American
Keyword tart
Dietary Restrictions Egg Free
Prep Time 40 minutes
Cook Time 8 minutes
Total Time 3 hours
Servings 8


For The Crust

  • 2 cups NILLA Wafers
  • ¼ cup sugar
  • 5 tablespoons butter melted
  • ½ cup flaked coconut sweetened

For the filling

  • 1 15-oz can sweetened condensed milk
  • ½ cup lime juice use key limes if available
  • 2 teaspoon gelatin
  • 2 tablespoon water
  • 2 cups heavy cream
  • 5 tablespoons sugar

For Garnish

  • 1 cup whipped cream reserved
  • ½ cup flaked coconut lightly toasted (optional)
  • lime sliced thin (optional)


For The Crust

  • Preheat oven to 350°.
  • Add NILLA Wafers and sugar to the bowl of a food processor and pulse until fine crumbs form.  Transfer to a medium bowl and add coconut flakes and melted butter.  Toss to combine completely.  Pour the crumbs into a 8″ tart pan with removable bottom.  Press the crumbs into the bottom and sides of the pan.  Bake for 8-10 minutes or until browned.  Set aside to cool completely.

For The Filling

  • In a large bowl, combine the sweetened condensed milk and lime juice.  Stir until thick and well incorporated.  Set aside.
  • Place the gelatin in a small bowl and cover with water.  Let stand two minutes to bloom.  Microwave in 10 second bursts until gelatin is dissolved.   Cool the gelatin to near room temperature, but do not let it set — very important.
  • Add the whipping cream to the bowl of a stand mixer (if you don’t have a stand mixer use a large mixing bowl and a handheld mixer)  Whip the cream for one minute on a medium speed. Slowly add the sugar to the cream.  Turn off the mixer and check to see that the gelatin has cooled, but not set.  Add the gelatin and continue to whip until stiff peaks form.  Separately reserve about 1 – 1 1/2 cups of whipped topping for garnish.
  • Spoon about 1/2 cup of whipped cream into the key lime filling and lightly stir to combine.  Add the rest of the whipped cream and fold completely into the mixture, careful not to deflate the cream too much.  
  • Pour the filling into the cooled pie crust and smooth over with a spatula.

For The Topping

  •  Add reserved whipped cream to a piping bag fitted with a large star tip.  Fold the end of the bag over once or twice to seal and use a steady pressure to pipe the whipped cream around the edge of the tart and in the center.  Sprinkle with toasted coconut and slices of key lime.  Refrigerate for at least two hours for a cloud like dessert. 
  • For a frozen tart — freeze at least two hours.  To serve, remove the tart from the freezer and let it sit out on the counter for 10-15 minutes to soften a little before slicing it.


If you don’t want to freeze the tart, just refrigerate it, it will be more mousse-like than firm and just as delicious.  Because we’ve stabilized the whipped cream, the tart will last in the refrigerator for up to 2-3 days.


Calories: 545kcal | Carbohydrates: 40g | Protein: 4g | Fat: 42g | Saturated Fat: 26g | Cholesterol: 106mg | Sodium: 202mg | Potassium: 154mg | Fiber: 2g | Sugar: 24g | Vitamin A: 1150IU | Vitamin C: 4.9mg | Calcium: 53mg | Iron: 0.4mg

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Looking for the ultimate springtime dessert. Try this Key Lime Mousse Tart which can be served chilled or as a semifreddo. Perfect for Easter & Mother's Day. #keylimepie #keylimemousse #easterdessert #mothersdaydessert

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  1. Beth Hutchinson says:

    I would like to make this for someone with a coconut allergy. Is there something I can substitute the coconut with?

    1. You can simply leave out the coconut in the graham cracker crust and for the the garnish. You can even use a premed graham cracker crust for convenience.

  2. 5 stars
    I have made this key lime pie for a number of occasions and have provided the your website for the recipe. Everybody loves it. I did make it with a graham cracker crust and do like the saltiness of this with the sweet pie. The coconut added to the crust makes it the best.

    1. I’m so glad you and your friends enjoy it. Have you tried it frozen yet? We love it that way — freeze it solid and then let it set out at room temperature for 10-15 minutes before slicing — it’s like a semi-freddo and even my “no-thank-you” on dessert, Aunt, went back for seconds!

  3. Can you. Substitute cool whip for the heavy cream and gelatin

    1. Hmmm. I have to be honest, I haven’t used Cool Whip in a very long time, but I’ve seen it used in other recipes before. I would think you could get away with it, but I’d serve it the same day as you make it — and make sure you’ve got enough people to eat the whole thing without leftovers… The stabilized whipped cream allows the tart to last for several days without deflation or ooze. I can’t say the same thing for Cool Whip…

  4. 5 stars
    Nilla Wafers and coconut! GENIUS! I am so sure that the Nilla Wafers up this recipe into the stellar category! Now to decide…. chilled or frozen?!? YUM!

    1. These are tough decisions, but you’ll win either way!

  5. I love ANYTHING Key lime! This looks so delicious and perfect for a spring dessert! What a lovely treat!

  6. I loooooove a good Key Lime Pie! This one looks amazing, too! The crust looks so great – love that you added shredded coconut to it!

    1. I always have coconut on hand and find that there are a lot of things that it pairs beautifully with!

  7. That is one beautiful tart! I just love the idea that you used Nilla wafers! I grew up snarfing on those sweet little beauties. This dessert would be perfect for my Easter table. I love how springy it is too.

    1. Glad you like it Julie — I agree – it’s ideal for Easter!

  8. Your pie looks so good, totally delicious. We can’t get Nabisco’s Nilla biscuits here in Australia, which I am totally bummed about.

    1. We’ll have to contact Nabisco and fix that!

  9. 5 stars
    Absolutely gorgeous pie. Loving the easy crust, so smart! We have key limes at the store now – time to get busy!

    1. Grab those limes and make it! Let me know how it comes out!

  10. 5 stars
    Lime and coconut? That sounds like an amazing combination! This tart looks heavenly and I guess time for me to take my tart pan out. Thanks for sharing.

  11. 5 stars
    This is so beautiful! I have never made key lime pie before. Now I will definitely attempt it!

  12. 5 stars
    We were in Florida for a wedding in March, and I got to devour some key lime pie! The one I had was thicker than this though- I should’ve stopped by your place and had some of yours!!!!

  13. Gabrielle Glatt says:

    5 stars
    I am definitely making this! I LOVE key lime pie ! Looks so easy, too!

  14. 5 stars
    What is not to love about this !!! The flavors are right there – especially the coconut Nilla crust. This is sure going to be a hit !!

  15. What a fun idea, using cookies in the crust! This pie looks absolutely amazing, my 10 yo happened to glance over while I was looking at it and now she’s begging me to make her one!

    1. Well – a cookie crust is nothing new, but I liked the coconut in there — it gave it a tropical nuance. I sent a photo to my college age daughter and she implored me to save her a piece.

  16. Love nilla and love these tarts! I swear I am going to be dreaming of biting into one all day now – must make!

    1. Thanks, Jenn! It’s perfect for entertaining!

  17. Luci's Morsels says:

    5 stars
    Excuse me while I wipe the drool from my mouth! This looks so amazing and delicious. It is also beautiful; ALMOST too beautiful to eat! Yummy! Luci’s Morsels | fashion. food. frivolity.

    1. Almost, but believe me, you’ll want to eat it!

  18. I have never had a key lime pie before, even when I was in key west. It looks so light and fresh.

    1. Well, you’ll either have to make this one — or come back for a visit!

  19. This looks phenomenal! Shopping list ready! Company dessert tomorrow! Thanks Lisa

    1. You are welcome! Let me know how it comes out!