Filling:

3 cups blueberries
1/4 cup sugar
1/2 tablespoon cornstarch
1/2 teaspoon lemon juice
1/8 teaspoon salt

Topping:

1/3 cup all-purpose flour
1/4 cup oats
1/4 teaspoon baking powder
1/4 teaspoon salt
3 tablespoons butter, softened
1/4 cup sugar

1. Mix blueberries, sugar, cornstarch, lemon juice, and salt in a bowl for the filling. Transfer to a baking dish.
2. Mix flour, oats, baking powder, and salt. Cream butter and sugar together; stir dry ingredients into butter.
3. Sprinkle topping evenly over filling. Bake at 375 until bubbly in the center about 30 minutes or until topping is brown.