Preheat oven to 400°F and grease a 9-inch round cake pan with nonstick cooking spray.
In a large bowl, mix together the Bisquick, egg, milk, sugar, and cinnamon. Stir until just combined.
Spread the batter into the prepared baking pan.
Top with fresh blueberries.
Prepare the crumb topping by adding the Bisquick, brown sugar, cinnamon and butter together in a medium bowl. Use a pastry blender or fork to blend then ingredients until the mixture resembles coarse sand.
Sprinkle the topping over the blueberries.
Bake in the preheated oven for 25 minutes, until a toothpick inserted in the center comes out clean.
Allow the cake to cool slightly before serving.
Notes
Please note: Nutritional values are estimates. Exact values depend on specific products used to make the recipe.