Preheat your oven to 350°F (175°C) and prepare a 9-inch springform pan with parchment paper.

In a mixing bowl, combine all-purpose flour, dark brown sugar, and ground cinnamon. Mix thoroughly.

Melt unsalted butter in a medium saucepan over medium heat, stirring frequently until golden brown.

In a large mixing bowl, whisk together the cooled brown butter and granulated sugar. Add the eggs one at a time.

Add the mashed overripe bananas, stirring gently, then alternate adding dry ingredients and wet ingredients until just combined.

Pour half of the batter into the prepared pan, sprinkle half of the cinnamon crumble, then layer remaining batter and crumble.

Bake for 45-50 minutes, until the top is golden brown and a toothpick comes out clean.

Let the cake cool for about 10 minutes, then transfer to a wire rack.

Prepare the glaze by whisking powdered sugar, milk, and vanilla until smooth.

Drizzle the glaze over the cooled cake, cut a slice, and enjoy!