Preheat oven to 400˚F. Grease 8 or 9-inch round layer pan. (Square will also work.)
Stir together 1-1/3 cup Bisquick and 3 tablespoons sugar in medium bowl. In separate bowl, melt 2 teaspoons butter in the microwave for 30 seconds. (I use a 2-cup Pyrex measuring cup). Add 1/2 cup cold milk and 1 egg to butter and whisk well. Combine liquids with Bisquick mixture and stir just until mixed. Spread in prepared pan. Don't worry if there doesn't seem to be enough batter. The topping adds a lot.
Mix 1/3 cup brown sugar, 1 teaspoon cinnamon, and 1/3 cup Bisquick with 1/4 cup softened or cold butter and distribute evenly over the top of the batter in the pan. OR mix sugar, cinnamon, and Bisquick together with a fork. Cut butter into dry ingredients with a fork or your fingers and sprinkle over the batter in the pan.
Bake at 400˚F (200˚C) until golden brown and a toothpick comes out clean. 13-14 minutes if using a 9-inch pan; 20-21 minutes if using an 8-inch pan.
Serve warm.
Notes
May be mixed the night before, covered and refrigerated before baking in the morning. Add a few extra minutes to baking time.