Peanut Butter Banana Muffins

Ingredients

• 1/2 cup unsalted butter
• 1/3 cup peanut butter
• 1 1/4 cups all-purpose flour
• 1/2 cup whole wheat flour
• 2 tsp baking powder
• 1 tsp cinnamon
• 1/2 tsp baking soda
• 3/4 cup granulated sugar
• 2 eggs
• 1 cup bananas (about 2 large, very ripe, mashed)
• 2 tsp vanilla
• 1/3 cup unsalted peanuts (chopped)