Preheat the oven to 350.
Mix blueberry muffin mix with milk and pour into a greased or lined 9x9 baking dish.
Mix flour, brown sugar and 2 tablespoons of melted butter or margarine together until it forms coarse crumbs.
Only add the extra 1 tablespoon if it looks too dry.
Distribute the crumb topping over the prepared coffee cake batter and bake for 35 minutes.
Let cool for 20 to 30 minutes before unmolding.
If desired drizzle with cream cheese frosting (Microwave for 30 seconds to make it pourable) leave this out for a less sweet cake.
