Step 1

Preheat oven to 350 degrees F (175 degrees C).

Step 2

In a medium bowl, combine flour, oats, brown sugar, cinnamon and melted butter. Stir until crumbly. Press half the oat mixture into a 9x13 inch baking dish. Cover with sliced apples.

Step 3

In a medium saucepan, combine white sugar, cornstarch, water and vanilla. Cook, stirring, until thick and clear, 10 minutes. Pour over apples. Cover apples with remaining crumble mixture.

Step 4

Bake in preheated oven 45 minutes, until bubbly and golden.