Dutch Apple Pie

I haven't made this in a while, hope it turns out well!

Ingredients

2 cups all-purpose flour
1 cup packed brown sugar
3/4 cup butter or margarine, melted
1/2 cup quick-cooking oats
FILLING:
2/3 cup sugar
3 tablespoons cornstarch
1 1/4 cups water
3 cups peeled, diced tart apples
1 teaspoon vanilla extract

Directions

Combine the first four ingredients; set aside 1 cup for topping. Press remaining crumb mixture into an ungreased 9-in. pie plate; set aside.
For the filling, combine sugar, cornstarch and water in a saucepan until smooth; bring to a boil. Cook and stir for 1 minute or until thickened. Remove from the heat; stir in apples and vanilla. Pour into crust; top with reserved crumb mixture. Bake at 350 degrees F for 40-45 minutes or until crust is golden brown.