Step 1

Preheat oven to 350°F. Lightly grease a 9x13-inch baking pan with cooking spray. Set aside.

Step 2

In a medium bowl, whisk flour, baking powder, baking soda, and salt. Set aside.

Step 3

In a large bowl, beat butter, granulated sugar, and brown sugar until light and fluffy. Add in eggs, mashed bananas, and vanilla bean paste/extract. Beat well.

Step 4

Slowly beat in flour mixture to banana mixture, ½ cup at a time, alternating with sour cream. Spread batter into prepared pan and set aside.

Step 5

To make the cinnamon streusel, in a medium bowl, stir together brown sugar, granulated sugar, cinnamon, melted butter and four until it resembles wet, crumbly sand. Sprinkle streusel evenly over top of batter.

Step 6

Bake for 40-50 minutes, or until toothpick inserted into center of cake comes out clean.