Preheat the oven to 350 degrees Fahrenheit. Grease a 9-inch pie pan.
In a large bowl, combine Bisquick baking mix, sugar, cinnamon, milk, and egg. Mix well.
Pour the mixture into the greased pie pan.
In a separate bowl, combine Bisquick baking mix, brown sugar, cinnamon, and butter with a blender or fork. You'll know it's done once you get a crumbly mixture. This is the topping for your coffee cake.
Spread the topping over the cake batter evenly.
Bake in the preheated oven for 25 minutes or until a toothpick comes out clean.
