01 - Preheat oven to 425°F. Line a 12-cup muffin tin with paper liners or lightly grease with cooking spray.
02 - In a large mixing bowl, whisk together flour, baking powder, baking soda, and salt until well blended.
03 - In a separate bowl, whisk melted butter, vegetable oil, granulated sugar, brown sugar, eggs, buttermilk, and vanilla extract until smooth and fully incorporated.
04 - Pour the wet ingredients into the dry ingredients. Mix gently with a spatula or wooden spoon until just combined. The batter should remain slightly lumpy—avoid overmixing to ensure tender muffins.
05 - Fold in 1 3/4 cups chocolate chips, reserving a small handful for sprinkling on top.
06 - Divide batter evenly among the 12 muffin cups, filling each cup completely to the top. This creates the signature bakery-style dome. Sprinkle reserved chocolate chips over each muffin.
07 - Bake at 425°F for 5 minutes to activate rapid rising. Reduce oven temperature to 350°F and continue baking for 13–15 minutes. Muffins are done when a toothpick inserted into the center comes out clean or with a few moist crumbs.
08 - Allow muffins to cool in the tin for 5 minutes before transferring to a wire rack. Cool completely before storing, or serve warm for maximum enjoyment.