Preheat your oven to 350ºF (175ºC) and grease a 9x13 baking dish.

In a mixing bowl, combine cold butter, all-purpose flour, granulated sugar, brown sugar, and cinnamon to make the crumb topping.

In a separate bowl, whisk together all-purpose flour, baking powder, cinnamon, and salt.

Cream softened butter and granulated sugar on medium speed until fluffy, then mix in eggs, vanilla extract, and mashed bananas.

Alternate adding the flour mixture and milk to the banana mixture until smooth.

Pour half of the batter into the greased dish, sprinkle with crumb topping, then add the remaining batter and crumb topping.

Bake for 50-55 minutes, checking for doneness with a toothpick.

Whisk powdered sugar and milk for glaze, then drizzle over cooled cake.