Preheat oven to 400°F. In a large bowl, toss the apple slices with the brown sugar, flour, lemon juice, cinnamon, and nutmeg until well combined. Cover and set aside. For best results, refrigerate the filling while you prepare the dough.
4 apples, 1/3 cup packed light brown sugar, 1 Tablespoon all-purpose flour, 2 teaspoons fresh lemon juice, 1 teaspoon ground cinnamon, 1/4 teaspoon ground nutmeg
On a lightly floured surface, roll out the puff pastry into a large rectangle (no need for perfection!). Transfer the dough to a 10-inch round skillet, or you can roll it directly onto parchment paper or a silicone baking mat. If the dough is too large, trim the excess and place it in the center of the skillet.
1 (13-16 ounce) package refrigerated puff pastry (we like Just Rol)
Fill the Galette: Spoon the apple filling (including any juices) into the center of the dough, leaving a 2-3 inch border around the edges. Arrange the apples however you like—either piled up or in a neat pattern like concentric circles.
Fold the edges of the dough over the apples, overlapping and pressing lightly to seal. Brush the crust with egg wash and sprinkle with coarse sugar if desired.
Chill the Galette: Refrigerate the assembled galette for 15-20 minutes (or up to 8 hours) before baking. Ensuring the galette is cold before baking helps maintain its shape.
Bake: Once chilled, bake the galette in the preheated oven for 35-40 minutes until golden brown and bubbly.
Serve: Enjoy with salted caramel and a scoop of ice cream for an extra indulgent touch!