Preheat the oven to 425 F.
Line a muffin tin with paper liners or grease with cooking spray.
In a medium bowl, mix together the flour, baking powder, and salt. Set aside.
In a large bowl, whisk together the melted butter, vegetable oil, and sugar until smooth.
Add in the sour cream and eggs, and whisk again until well combined.
Stir in the vanilla extract.
Gradually add the dry ingredients into the wet ingredients, and whisk until just combined.
Fold in the chocolate chips nto the batter, and mix everything together until just combined. Don’t overmix.
Let the batter sit for 15 min at room temperature then spoon the batter into 4 muffin cups, only fill every other muffin cup well with batter.
Sprinkle a generous amount of sugar on top of each muffin
Bake for 9 minutes at 425F and then lower the heat to 350F and continue baking it for another 18 minutes, or until a toothpick inserted in the center of a muffin comes out clean.
Remove from the oven and let cool for a few minutes before transferring to a wire rack to cool completely.
