Preheat oven to 350 F. Grease and flour a 9x13” baking pan and set aside.

Prepare the topping by mixing together the bisquick, brown sugar, and cinnamon, then cut in the butter; set in the fridge until needed.

In a large bowl whisk together the bisquick, sugar, egg, sour cream, milk, and vanilla until smooth. Batter will be sticky.

Spread about ½ the batter into the prepared pan, it will be a thin layer.

Add about half the cinnamon topping, then add the remaining batter in small dollops on top. Carefully smooth the remaining batter over the cinnamon filling. Top with remaining crumble mixture.

Bake in the preheated oven for 40 minutes, or until a toothpick inserted in the center comes out clean.

Add the cream to the powdered sugar, and mix until smooth, then drizzle over the cooled cake

Allow the glaze to set for 15 minutes before serving the cake.