Preheat the oven to 400°F (200°C). In a large bowl, sift together the flour, baking powder, and salt.
Add the lard to the flour mixture and cut it in using a pastry cutter or your fingertips until the texture resembles coarse crumbs.
In a measuring cup, combine the water, egg yolks, and lemon juice. Pour this mixture over the flour mixture and gently blend with a fork until combined. The dough will be moist.
Divide the dough in half. Roll or pat one half directly into a 9×13-inch jelly roll pan, pressing it slightly up the sides.
Evenly spread the apple dessert filling over the dough.
Roll out the remaining dough to fit the top. Carefully flip it over the apple filling and press or pinch the edges together. If the dough doesn’t seal completely, patch where needed, but ensure the top is fully covered. Cut several slits in the top dough to allow steam to escape.
Bake for 40 minutes, rotating the pan halfway through, until the crust is golden brown. Remove from the oven and cool on a wire rack.
While the apple slices cool, make the glaze. In a bowl, whisk together the powdered sugar, melted butter, vanilla, and milk until smooth. Add more milk if necessary to reach a spreadable consistency.
Spread the glaze over the top of the crust using an offset spatula. Let the glaze set and harden before cutting the apple slices into 2- or 3-inch squares. Enjoy!