Preheat the oven to 350 F.
Combine the shortbread base and crumble topping ingredients in a food processor until they become well incpororated and crumbly in texture.
Combine the blueberry filling ingredients. If using frozen blueberries, microwave until thawed before mixing with other ingredients.
Take 3/4 of the shortbread mixture and press it firmly into the bottom of a greased 9x9 baking pan.
Spoon the blueberry mixture on top of the base.
Using your fingers, sprinkle the crumble mixture on top of the blueberries.
Bake for 35 minutes or until the crumble is brown and the blueberry mixture is thick and bubbling.
Let cool before slicing into slices and serving warm or chilled.