Step 1: Prep the Oven and Pan
Preheat your oven to 350°F. Lightly spray an 8×8-inch pan with oil, then line it with parchment paper, allowing the paper to extend up the sides to create handles.

Step 2: Combine Wet and Dry Ingredients
In a small bowl, thoroughly mash the bananas. In a separate small bowl, whisk together the flour, baking soda, salt, and cinnamon until well combined.

Step 3: Cream Butter and Sugar
In a large bowl, use an electric mixer to cream the room-temperature butter and brown sugar until the mixture is visibly light and fluffy.

Step 4: Mix in Remaining Wet Ingredients
Mix in the egg, vanilla extract, and sour cream, adding them one at a time and ensuring each ingredient is incorporated before adding the next. Then, stir in the mashed bananas.

Step 5: Add Dry Mix and Bake
Finally, mix in the dry ingredients just until all traces of flour streaks disappear. Do not over-mix. Pour the batter into the prepared pan. Bake for 22–28 minutes, or until a toothpick inserted into the center comes out clean. Let the cake cool completely in the pan on a wire rack.

Step 6: Prepare Peanut Butter Honey Frosting
In a medium bowl, mix together the softened butter, creamy peanut butter, honey, and powdered sugar until the mixture is smooth.

Step 7: Adjust and Frost
If the frosting is too thick, gradually add the heavy whipping cream or milk (starting with 1/2 tablespoon) until you achieve a smooth, spreadable consistency. Spread the finished frosting evenly over the completely cooled cake. Slice into squares and serve.