- 1/4 cup (1/2 stick) salted butter
- 1/2 vanilla bean, split lengthwise
- Basic Tart Dough
- All-purpose flour (for dusting)
- 1 pound baking apples (such as Pink Lady; about 2 large), scrubbed, sliced 1/8″ thick
- 3 tablespoons dark muscovado or dark brown sugar
- 1 large egg
- 1 tablespoon granulated sugar
- 2 cups heavy cream
- 2 tablespoons pure maple syrup
- Place a rack in middle of oven and preheat to 375°. Place butter in a small saucepan and scrape in vanilla seeds; add pod. Cook over medium heat, stirring often, until butter foams, then browns (be careful not to burn), 5-8 minutes. Remove pan from heat and remove pod.
- Roll out dough on a lightly floured surface into a rough 14×10″ rectangle about 1/8″ thick (alternatively, roll out into a 12″ round). Transfer to a parchment-lined baking sheet. Arrange apples on top, overlapping and leaving a 1 1/2″ border. Brush apples with brown butter and sprinkle with muscovado sugar. Lift edges of dough over apples, tucking and overlapping as needed to keep rectangular shape.
- Beat egg with 1 teaspoon water in a small bowl and brush crust with egg wash. Sprinkle with granulated sugar and bake, rotating once, until apples are soft and juicy and crust is golden brown, 40-50 minutes. Let cool slightly on baking sheet before slicing.
- Beat cream in a medium bowl to medium-soft peaks. Fold in maple syrup and serve alongside galette.
- Do ahead: Galette can be baked 2 days ahead. Store tightly wrapped at room temperature. Reheat slightly before serving.