• Preheat oven to 350 degrees Fahrenheit. Line a square baking pan with parchment paper or spray with non stick baking spray.

To prepare the crumb topping

• In a small mixing bowl prepare the crumb by mixing together ½ cup light brown sugar, ½ cup all-purpose flour and ½ teaspoon ground cinnamon, and 3 tablespoons melted butter. Stir to combine. Then using a fork mix until large crumbs are formed. Set aside.

To make the banana cake

• In a large mixing bowl add ½ cup room temperature unsalted butter, ½ cup granulated sugar and ½ cup light brown sugar. Cream together. Add in 2 large eggs and 1 teaspoon vanilla extract. Stir to combine.
• Mash 3 mashed ripe bananas with a fork, then add to the batter, stir to combine, will be slightly lumpy.
• In a medium size mixing bowl combine 2 cups all-purpose flour, ½ teaspoon baking powder, ½ teaspoon baking soda, ½ teaspoon salt, ½ teaspoon ground cinnamon, stir with a fork to mix.
• Add to the sugar mixture, and stir slowly and pour in ⅔ cup buttermilk while stirring. Stir until just combined.
• Pour the batter into the prepared baking pan and sprinkle the crumbs on top. Gently press the crumbs into the batter to help stick.
• If using an 8x8 pan bake for about 45-50 minutes. If using a 9x9 pan bake for about 35-40 minutes.
• Allow to cool for about 30 minutes prior to serving. If desired top with icing.