2 ½ cups all-purpose flour
4 teaspoons sugar
¼ teaspoon fine salt
14 tablespoons cold unsalted butter, diced
1 large egg, lightly beaten with 2 tablespoons cold water
2 tablespoons freshly squeezed lemon juice
6–7 baking apples like Golden Delicious or Granny Smith
1 cup sugar, plus more for sprinkling on the tart
½ stick unsalted butter
¼ teaspoon ground cinnamon
A generous pinch of ground nutmeg
1 large egg, lightly beaten