Preheat oven to 375F (190C) and line muffin tin with paper liners (out of paper liners? See my tutorial on how to make the muffin liners seen in the photos above).

Combine peanut butter, sugars, and oil, and stir well to combine. 1 ¼ cups (250 g) creamy peanut butter, ½ cup (100 g) granulated sugar, ½ cup (100 g) light brown sugar, ½ cup (118 ml) vegetable or canola oil

Add eggs and stir well, then stir in buttermilk and vanilla extract.2 large eggs, 2 teaspoons vanilla extract, 1 cup (236 ml) buttermilk¹

In a separate bowl, whisk together flour, baking powder, and salt.2 cups (250 g) all-purpose flour, 1 Tablespoon baking powder, 1 teaspoon salt

Combine wet and dry ingredients and use a spatula to gently fold together. Once batter is about halfway combined, add chocolate chips and continue to stir until better is uniform (don't over-mix or muffins will be dense and dry).2 cups (340 g) milk or semisweet chocolate chips

Divide batter into muffin liners, filling each cavity ¾ the way full (keep in mind this recipe makes 18 muffins, so you will need two tins. If you only have one, bake the first batch and cover the remaining batter until the first batch has baked and mostly cooled). If desired, sprinkle muffins with additional granulated sugar.Additional granulated sugar for sprinkling on top

Bake on 375F (190C) for 20-22 mins or until a toothpick inserted in the center comes out clean (avoid chocolate chips) or with moist crumbs. Do not over-bake or they will be dry.