Roll out the second half of the dough and place it over the apple mixture. Cut slits in the top crust to allow steam to escape.
Bake for 45-50 minutes, or until the crust is golden brown and the apples are tender.
Allow the bars to cool before cutting into squares.
For a richer flavor, try adding a handful of chopped walnuts or pecans to the oat topping. If you prefer a sweeter filling, mix in a tablespoon of honey with the apples. For a touch of tartness, use a mix of sweet and tart apples, such as Granny Smith and Honeycrisp. To make this recipe gluten-free, substitute the all-purpose flour with a gluten-free flour blend and ensure your oats are certified gluten-free.