Make Crumble
Combine oats, flour, brown sugar, cinnamon, and salt.
Stir in melted butter until moistened and clumps form.
Chill 30 minutes (refrigerator) or 10 minutes (freezer).
Make Filling
Combine sugar and cornstarch.
Stir in blueberries, vanilla extract, and lemon juice.
Bake Crumble
Preheat oven to 350˚.
Place filling in dish.
Top evenly with crumble.
Bake 45 minutes.
Rest 15 minutes.
