01 -
Set the oven to 375°F (190°C). Grab a 9x13-inch pan and either spray it with nonstick spray or coat it with butter.
02 -
Toss the apple slices into a bowl. Sprinkle flour, cinnamon, and brown sugar on top. Gently mix until every slice is covered. Leave this aside for now.
03 -
In a medium-sized bowl, mix oats, flour, cinnamon, and brown sugar. Drop in the butter chunks. Using your fingers or a fork, mix the butter into the dry ingredients until it looks crumbly, with butter bits the size of peas.
04 -
Take 3 cups of that crumb topping and press it flat onto the bottom of the prepared pan. Layer the apple mix on top, pressing down a bit with a rubber spatula. Add the rest of the topping and spread it evenly over the apples.
05 -
Without covering, bake for about 35-45 minutes. You’ll know it’s ready when you see bubbling fruit and a golden top.
06 -
For the best taste and texture, serve while it’s still warm.