Preheat oven to 350 degrees.
Whisk together flour, baking soda, and salt in a medium bowl.
Using an electric mixer on medium-high speed, beat butter and both sugars until fluffy.
Add eggs, one at a time, scraping down sides of bowl as necessary.
Beat in banana, sour cream, and vanilla extract.
With mixer on low, beat in flour and mini peanut butter cups.
Pour into a greased 5X9-inch loaf pan. Bake for 50 to 60 minutes.
Mix together peanut butter and sugar. Microwave until melted. Let cool slightly and place in a ziptop bag. Snip one of the corners and drizzle the glaze on top of the bread.