Preheat oven to 350 degrees F.

Prepare a 9x5 inch loaf pan by lining with parchment paper so it hangs off the long sides of the pan but not the short. Grease thoroughly with cooking spray.

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

In the bowl of a stand mixer fitted with the paddle attachment, cream together the butter and sugar on medium-high speed for 4-5 minutes, until light in color and fluffy.

Scrape down the sides of the bowl with a rubber spatula and add eggs one at time on medium-low speed, completely combining between each egg addition.

Scrape down the sides of the bowl and add sour cream and vanilla. Mix over medium-low speed until completely combined.

Scrape down the sides of the bowl and add the bananas and mix on medium-low until there are no visible banana chunks.

Scrape down the sides of the bowl. On low speed, gradually add in the dry ingredients until completely mixed, but do not over mix.

In a medium bowl, add all ingredients for the streusel and use a fork or your fingers to mix together until crumbly.

Pour the banana bread batter into your prepared pan. Top with streusel mixture.

Bake the bread for 1 hour 15 minutes to 1 hour 30 minutes, until completely baked through. You should be able to wiggle the loaf pan with no jiggling of the center of the loaf.

Remove from oven and place on wire rack to cool. Cool completely before serving.