Preheat oven to 350°F (177°C) and grease a 9x5-inch loaf pan.

Melt 1/2 cup unsalted butter and let it cool slightly; add 1 cup granulated sugar and mix well.

Crack in 2 large eggs and pour in 1 teaspoon vanilla extract; stir until smooth.

Fold in 1 cup mashed ripe bananas.

In a separate bowl, whisk together 1 1/2 cups all-purpose flour and 1 teaspoon baking soda; gradually fold this into the banana mixture.

In a small bowl, combine 1/4 cup melted butter, 1/2 cup granulated sugar, 1/4 cup brown sugar, and 2 teaspoons ground cinnamon.

Layer approximately 1/4 of the banana batter in the loaf pan, then dollop some cinnamon sugar mixture on top; repeat twice more.

Slice a banana and place the pieces down the center of the batter before baking.

Bake for 60-70 minutes until golden brown and a toothpick comes out clean.

Cool in the pan for about 30 minutes before transferring to a wire rack to cool completely.