Preheat oven to 350°F.
Place the bacon in a medium, nonstick skillet over medium-high heat. Stir occasionally with a wooden spoon until the fat starts to render, about 4 minutes. Cook for about 5 more minutes until the fat begins to froth and the bacon gets crispy. Remove the bacon to a plate with a slotted spoon and drain on paper towels. Empty the bacon fat into a glass liquid measuring cup and let cool.
In a mixing bowl, combine flour, baking soda, salt and cinnamon. Set aside. Mash the bananas in a separate bowl until smooth.
In a stand mixer fitted with a paddle attachment, cream together butter, a quarter cup of the cooled bacon fat and the sugar for 3-5 minutes at medium speed, or until fluffy. Add in eggs one at a time until mixture is fully combined. Add in vanilla, sour cream and mashed bananas. Turn down to low speed and add flour mixture in batches.
Spray a 9x5-inch loaf pan with cooking spray. Pour the batter into the pan and bake for 1 hour or until a toothpick comes out clean.
While the bread is cooking, whisk together peanut butter, powdered sugar and water, a tablespoon at a time, in a small bowl until smooth and shiny. If the glaze is too thick to pour, add another tablespoon of water.
When the bread has cooled to room temperature, pour the peanut butter glaze over the banana bread and sprinkle with the reserved bacon bits.