• Preheat oven to 350F
• Line a 9 inch cake pan with parchment paper and spray with baking spray
• In a medium bowl mix together flour and baking soda
• In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter, brown sugar and granulated sugar - Cream until light and fluffy
• Add in the egg and vanilla and mix until combined
• Scrape down the sides of the bowl
• Beat in the peanut butter
• Alternate adding in the flour and the milk. Add in some flour, then some milk, the rest of the flour, the rest of the milk
• Beat in the sour cream

For the banana layer

• Melt your butter and mix in the brown sugar, vanilla and cinnamon
• Stir until combined - The butter may start to seperate a little but this is okay!
• Spread this mixture on the bottom of your cake pan in an even layer
• Slice your bananas about 1/4 inch thick and place them in an even layer on the bottom of the cake pan on top of the brown sugar and butter mixture.
• Pour the cake batter carefully on top of the bananas and spread into an even layer. Gently so you do not disturb the bananas. We recommend using a spatula for this step.
• Bake for 20 minutes or until a toothpick inserted comes out clean.
• Let cool for 15 minutes before flipping out of the pan
• Carefully peel the parchment paper off of the top