Preheat oven to 350°F (175°C). Grease and line your cake pan with parchment paper.
Mix dry ingredients: In a bowl, whisk flour, baking soda, baking powder, salt, and cinnamon.
Cream butter & sugar: Beat butter and brown sugar until fluffy. Add eggs one at a time, then vanilla.
Combine wet & dry: Alternately add mashed bananas and dry ingredients to the butter mixture. Fold in yogurt.
Bake: Pour batter into the pan. Bake for 45–50 minutes (or until a toothpick comes out clean).
Cool: Let it rest in the pan for 10 minutes, then transfer to a wire rack.