Measure the dry ingredients into a small bowl and using a pastry cutter, cut in the butter until the mixture is crumbly. Set aside.
After the pizza crust has been partially baked for 6 minutes, spoon the pie filling over the top, followed by the crumble topping.
Bake an additional 7 minutes. Turn the oven up to broil and broil for about 1 minute and broil the pizza just to get the crumble topping crispy. Watch closely so it doesn’t burn.
Remove from oven and set the pan on a wire rack. Allow to cool about 10 minutes while you are preparing the icing.
2 teaspoons butter, softened
3/4 cup powdered sugar
2 tablespoons milk (or more, if needed)
½ t. vanilla
Whisk together the butter and a small amount of powdered sugar to form a paste. Add milk and vanilla. Whisk in additional powdered sugar or more milk if needed, just until it is a nice consistency to drizzle.
Cut into wedges and serve while still warm.