Sandwiching the puff pastry between two baking sheets ensures that the pastry rises perfectly even.
Ingredients
1 package frozen puff pastry, thawed in refrigerator
All-purpose flour (for surface)
1 large egg, beaten to blend
2 tablespoons sugar, plus more for sprinkling
Nonstick vegetable oil spray
3 Pink Lady apples, scrubbed, thinly sliced crosswise into 1/8" rounds, seeds removed
2 tablespoons apple cider vinegar
2 teaspoons vanilla extract
Pinch of kosher salt
1/3 cup pure maple syrup, plus more for serving
3 tablespoons bourbon or applejack brandy, divided
4 tablespoons unsalted butter, cut into pieces
1 cup chilled heavy cream
Directions
Preheat oven to 400°F. Roll out pastry on a lightly floured surface to flatten and smooth creases. Trim slightly to make clean, straight edges; cut into 16 squares or rectangles. Transfer to a parchment-lined rimmed baking sheet; brush with egg and sprinkle with sugar. Coat another sheet of parchment with nonstick spray and place, oil side down, on top of pastry; top with another rimmed baking sheet. Bake until pastry is deep golden brown and puffed, 20–25 minutes. Let cool.
Reduce oven temperature to 350°F. Toss apples, vinegar, vanilla, salt, 1/3 cup maple syrup, and 2 tablespoons bourbon in a shallow 3-quart baking dish; dot surface with butter. Cover tightly with foil and bake until apples soften and have released their juices, 30–35 minutes. Remove foil, baste apples with juices, and roast until apples are very tender and curled around the edges and a thin layer of juice covers the bottom of the dish, 20–25 minutes.
Just before serving, whisk cream and remaining 2 tablespoons sugar in a small bowl to medium peaks. Whisk in remaining 1 tablespoon bourbon.
Let guests assemble individual mille-feuille, topping pastry with apples, whipped cream, and a drizzle of maple syrup.
Apples can be baked 2 hours ahead. Let cool; store tightly wrapped at room temperature. Gently reheat before using.
