Whisk all dry ingredients together and set them aside.
2½ cup All-purpose flour, ¼ cup Cornstarch, 3 teaspoon Baking powder, ½ teaspoon Baking soda, ½ teaspoon Salt
Use the whisk attachment to beat the sugar, eggs, and vanilla extract until light and fluffy.
2 Eggs, 1 cup Sugar, 1 tablespoon Vanilla extract
Whisk melted butter, oil, buttermilk, and sour cream in a measuring cup and add to the above mixture.
¼ cup oil, 1 cup Buttermilk, ½ cup Sour cream, ½ cup Butter
Gently fold in the flour mixture and the chocolate chips and mix. Do not overmix the batter. Cover the batter with cling wrap and let it rest for an hour. You can leave the batter in the fridge overnight.
1 cup Mini chocolate chips
Preheat the oven to 450℉ and line a 12-cavity muffin pan with muffin liners. Set it aside.
Fill up the muffin liners to the top. For extra crunch, sprinkle some turbinado sugar and a few more chocolate chips before baking.
2 tablespoon Turbinado sugar
and bake them at 450℉ oven for 5-7 minutes, then bring the temperature down to 350℉ and bake for another 10 minutes. Let them cool down before serving.