Step 1

Position rack in the center of your oven. Preheat to 400° F/200°C. Coat the insides and the tops of 12 standard sized muffin tins with nonstick spray; set aside.

Step 2

Whisk the flour, baking soda and salt together in a bowl and set aside.

Step 3

Cream the peanut butter and brown sugar in a large bowl with an electric mixer until smooth and creamy, about 2 minutes. Beat in vanilla, then beat in eggs one at a time, until incorporated. Scrape down bowl as needed.

Step 4

Alternately add the dry mixture and the “buttermilk” to the peanut butter mixture, beating gently, just until incorporated. Peel the bananas. Slice one-and-a-half of the bananas directly into the batter, making the slices about 1/8-inch (3 mm) thick. Fold them into the batter.

Step 5

Scoop batter into muffins tins - we use an ice cream scoop - dividing equally. Slice the remaining half a banana and place slices on top of each muffin, then sprinkle the chopped peanuts on each muffin, also dividing equally.

Step 6

Bake for about 18 to 22 minutes. A toothpick should test clean when inserted in center; the tops will spring back when gently pressed.

Step 7

Cool pan(s) on rack for 5 minutes, then turn out and cool further on rack. Muffins are ready to eat warm, or cool completely and store in an airtight container at room temperature for up to 3 days.