Preheat oven to 425℉. Spray a baking sheet with vegetable spray and set aside.
Slice 1 pound Dutch baby potatoes in half, lengthwise and transfer to a mixing bowl.
In a medium bowl, combine 2 tablespoons whole grain Dijon mustard, 3 tablespoons olive oil, 2 garlic cloves, 1 tablespoon fresh rosemary, ½ teaspoon lemon zest, ½ teaspoon kosher salt and ½ teaspoon black pepper. Whisk to combine. Add potatoes and toss until potatoes are well coated.
Arrange potatoes in a single layer on the baking sheet, flesh side down (this promotes a nice browning and crisping).
Roast for 15 minutes. Use a metal spatula to flip the spuds. Remove any burnt bits of the mustard dressing.
Return the potatoes to the oven and continue cooking for an additional 15 minutes, until crispy on the outside and tender inside. Sprinkle with 2 teaspoons parsley. Serve.
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Notes
To prevent the dressing from burning, arrange the potatoes over the dressing where you can.
Scrunch the potatoes together, rather than spreading them out on the baking sheet for the first 15 minutes.
These potatoes are excellent served hot but also can be served at room temperature with a chop of fresh parsley.