▢1 cup sugar ▢½ cup unsalted butter softened ▢½ cup creamy peanut butter divided ▢2 eggs ▢1 teaspoon vanilla extract ▢3 tablespoons milk ▢2 cups all-purpose flour ▢½ teaspoon salt ▢½ teaspoon baking soda ▢1 teaspoon baking powder ▢3 bananas overripe and mashed
Preheat the oven to 325°F. Grease a 9 x 5 loaf pan and line with parchment paper, then set aside.
In a large bowl or the bowl of a stand mixer, cream together the sugar, butter, and ¼ cup peanut butter until light and fluffy. Add the eggs, vanilla, and milk, and mix until smooth.
Add the flour, salt, baking soda, and baking powder, and mix until just combined. Fold in the mashed bananas and pour into the prepared loaf pan.
Scoop the remaining ¼ cup peanut butter into a ziplock bag, and cut the corner off the bag. Pipe three lines of peanut butter across the top of the batter, then drag a toothpick or skewer through the batter to swirl the peanut butter.
Bake 60-70 minutes, or until a toothpick inserted into the center of the loaf comes out clean.