6 Tablespoons salted butter, melted and cooled for a minute
Instructions
Preheat oven to 350°F. Grease a 9x9 square baking pan.
Stir together flour, cinnamon, baking soda, and baking powder. Set aside.
With an electric mixer, beat the butter until smooth.
Add in the granulated sugar and beat until combined. Scrape down the side of the bowl as needed.
Add in egg and vanilla and beat until smooth.
Add in mashed banana and yogurt and mix until combined.
Add in the dry ingredients and mix until just combined. Don't mix too much or the batter will become tough.
Pour half of the batter into the prepared and pan and spread it into an even layer.
Mix together the 2 T. of brown sugar and 1½ t. cinnamon for the Cinnamon Filling.
Sprinkle the Cinnamon Filling over the batter in the pan.
Sprinkle ⅓ cup of the chocolate chips over the Cinnamon Filling.
Pour the remaining batter into the pan and spread it into an even layer.
Sprinkle the remaining ⅓ cup of chocolate chips on top of the batter.
Make the streusel topping next by combining the dry ingredients with a whisk and then gradually stirring in the melted butter until you have moist crumbs. You may not use all of the melted butter. If the mixture becomes too wet, add a Tablespoon of flour one at a time until it drys out a little.
Crumble the streusel mixture on top of the chocolate chips in the pan.
Bake for 25 minutes and then cover with aluminum foil to make sure the streusel does not burn. Bake for an additional 15 - 25 minutes until a toothpick comes out clean.
Let cool.
Cover and store at room temperature.
Notes
Layer Order from bottom to top: Half the cake batter Cinnamon Filling Half the chocolate chips Half the cake batter Half the chocolate chips Streusel Topping
Recipe by Birch Tree Baking at https://www.birchtreebaking.com/banana-chocolate-chip-crumb-cake/