Preheat Oven: Preheat oven to 350°F (175°C). Grease a 9x5-inch loaf pan or line with parchment paper.
Mix Dry Ingredients: In a medium bowl, whisk together flour, baking soda, and salt. Set aside.
Cream Butter and Sugars: In a large bowl, cream together softened butter, peanut butter, and sugar until light and fluffy.
Add Eggs and Bananas: Beat in eggs one at a time, then stir in mashed bananas and vanilla extract until combined.
Combine Wet and Dry Ingredients: Gradually add the dry ingredients to the wet mixture, alternating with milk, beginning and ending with dry ingredients. Mix until just combined.
Add Mix-Ins: Gently fold in chocolate chips or nuts if using.
Transfer to Pan: Pour batter into prepared loaf pan and smooth the top with a spatula.
Bake: Bake for 60–70 minutes, or until a toothpick inserted into the center comes out clean.
Cool: Allow bread to cool in the pan for 10 minutes, then transfer to a wire rack to cool completely before slicing.