Step 1

Begin by preheating the oven to 350 degrees F. Spray a 9x13-inch baking dish with baking spray. Set aside.

Step 2

In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.

Step 3

In a large bowl, cream together the butter, sugar, and brown sugar, with an electric mixer until smooth. (This will take about three minutes.) Add the eggs, one at a time, beating well after each addition. Add the sour cream and vanilla. Beat to combine.

Step 4

Add the prepared dry ingredients to the wet ingredients. Beat to combine. (Usually, this takes about 2 minutes at medium speed.)

Step 5

Pour half of the batter into the prepared baking dish. Spread in an even layer with a spatula.

Step 6

In a small bowl, prepare the topping by whisking together the sugar and cinnamon. Sprinkle half of this mixture on the batter. Top with half of the chocolate chips.

Step 7

Add the remaining batter and spread it into an even layer with a spatula. Sprinkle the batter with the remaining cinnamon-sugar mixture and chocolate chips.

Step 8

Bake for 35-40 minutes or until a toothpick inserted near the center comes out clean. Do not overbake.

Step 9

Allow the cake to cool before serving. Cut into 12 pieces for larger servings or 18 pieces for smaller treats.