Preheat the oven to 350 degrees F. Spray an 8-inch square baking dish with cooking spray and lightly dust with flour. Set aside.
In a medium saucepan over medium heat, melt ½ cup butter until it turns medium-brown in color and has a nutty aroma.
Remove from the heat and allow it to cool to room temperature.
In a small bowl, whisk together ⅓ cup all-purpose flour, ¼ cup brown sugar, ½ teaspoon cinnamon, and ¼ teaspoon salt.
Mix in the 3 ½ tablespoons softened butter until the mixture is crumbly and stir in the ½ cup pecans. Set aside.
Using a stand mixer with the paddle attachment, mix together the 2 large eggs, 1 large banana, ½ cup crushed pineapple, and 1 teaspoon vanilla extract until combined. Add in the ½ cup browned butter and continue mixing until combined.
In a separate small bowl, whisk together the 1 ½ cups all-purpose flour, ¾ cup granulated sugar, ¼ cup brown sugar, ¾ teaspoon salt, ¾ teaspoon baking powder, and ½ teaspoon ground cinnamon.
Slowly add the flour mixture into the egg mixture and continue mixing on low speed until combined.
Sprinkle with half the streusel mixture at the bottom of the prepared baking pan.
Top with ½ of the cake mixture and spread evenly.
Sprinkle with the other half of the streusel mixture and top evenly with the rest of the cake mixture.
Place in the oven at 350 degrees F. and bake 40 to 45 minutes, until a cake tester comes out clean. Remove from oven and all to cool in the pan on a cooling rack for 10 to 15 minutes. Run a knife along the edges of the cake and remove from the pan.
Make the glaze in a small bowl, whisk together the ½ cup powdered sugar, 2 tablespoons sour cream, and 1 ½ teaspoons milk until smooth. Drizzle evenly over the top of the cake while still warm.