If you want an ultra-creamy creamed spinach recipe, this steakhouse-style creamed spinach is the best. You can use fresh or frozen spinach for this luxurious side dish and don't forget the secret ingredient!
Fill a large bowl with ice and add cold water to cover. Set aside.
Bring a saucepan of water to a boil over high heat. Add 1 teaspoon kosher salt. Working in batches, add the spinach a few handfuls at a time. Blanch the spinach for about 30 seconds, then use a kitchen spider or tongs to transfer the spinach leaves to the ice bath. Continue cooking the rest of the spinach and shocking it in the ice bath.
Transfer the spinach to a fine mesh colander and press against the cooled spinach to drain. Transfer spinach to several paper towels, stacked together or an old (but clean) dish towel. Squeeze any remaining liquid from the blanched spinach.
Transfer the spinach to a cutting board and roughly chop it. Set aside.
In a skillet over medium heat, add the butter to melt, then stir in the minced shallots. Cook for 3-4 minutes or until the shallots are softened and translucent.
Sprinkle the flour over the shallots and cook and stir for one minute or until there are no dry bits of flour left in the pan. Add the milk a little at a time, stirring constantly and cook until it thickens.
Add the kosher salt, black pepper and nutmeg and stir to combine.
Add the chopped spinach to the bechamel sauce and mix well. Remove the pan from the heat and stir in the Boursin cheese, mixing until the cheese has melted into the sauce. Serve.