01 -
Preheat the oven to 350°F. Grease an 8 x 8 x 2-inch square cake pan or a 9 x 2-inch round cake pan (both should hold 8 cups of volume).
02 -
Spread 2/3 cup brown sugar on the bottom of the pan and scatter pieces of butter (4.5 tablespoons). Place the pan in the oven for 5-7 minutes until the butter has melted. Remove from the oven, stir to combine melted butter and sugar, and spread evenly on the bottom. Arrange banana slices to cover the base. Set aside.
03 -
In a bowl, stir together the all-purpose flour, whole wheat flour, baking powder, baking soda, ground cinnamon, and salt. Set aside.
04 -
In a large bowl, cream together the softened butter and granulated sugar. Add eggs and vanilla extract, mixing to combine. Add Greek yogurt and mashed bananas, mixing until fully incorporated.
05 -
Turn your mixer to low speed and gradually add the dry mixture into the wet mixture. Mix just until combined. Do not overmix.
06 -
Pour the batter over the prepared bananas in the pan and smooth the top. Bake at 350°F for 30 minutes, then reduce the oven temperature to 325°F and bake for an additional 25-35 minutes, or until a toothpick inserted into the center comes out clean.
07 -
Let the cake cool in the pan completely, or at least until the bottom is barely warm. Use a knife to loosen the edges from the pan. Place a plate upside down on top of the pan and invert the cake onto the plate.