Preparation
Filling: Preheat oven to 375 degrees F. Place the butter in an 8x8-inch square glass baking dish (no substitutes), and melt the butter in the microwave. In a mixing bowl, combine lemon juice and blueberries. Add the sugar and mix well. Add the blueberry mixture to the baking dish with the melted butter. Do not stir.

Topping: Combine all of the topping ingredients in a small bowl. Pour this mixture over the blueberries and bake 45 minutes, or until brown.

Serve with fresh whipped cream or vanilla ice cream.