This simple, classic dessert recipe is easy to put together. It's delicious served warm with a scoop of vanilla ice cream!
Preheat the oven to 375º F.
To prepare the filling, toss the fresh or frozen blueberries with the 3 tablespoons of flour and 1-4 tablespoons of sugar. Pour the filling into a 2-quart square baking dish.
For the topping, in a medium bowl, combine the oats, brown sugar, flour, and cinnamon. Cut in the butter with a fork or a pastry blender until it forms large crumbs.
Pour the filling on top of the fruit, and bake for 30-35 mins until the topping is golden and crisp.