Preheat the oven to 350°F. Prepare your cupcake pan with cupcake liners.
Mix all dry ingredients and set aside.
2½ cups All purpose flour, 3 teaspoon Baking powder, 1 teaspoon Salt, 1 tablespoon Corn starch
Mix the buttermilk and milk, set aside.
1 cup Milk, ¼ cup Buttermilk
Set your stand mixer on whisk attachment. In a large mixing bowl, beat together the sugar, vegetable oil, eggs, and vanilla extract until well incorporated. Scrape down the bowl as needed.
2 cups Sugar, 3 Eggs, ½ cup Oil, 1 tablespoon Vanilla extract
Add the sour cream and mix well.
½ cup Sour cream
Add the dry ingredients, alternating with the milk mixture in three passes—two wet and three dry ingredients. Start and finish with dry ingredients. Do not overmix the batter.
½ cup Sprinkles
Now put back the bowl on the mixer and with the whisk attachment, mix the batter for only 15 seconds. To make sure all the ingredients are incorporated. DO NOT OVERMIX.
Scoop the batter into the cupcake liners and bake for 15-18 minutes. Until an insert comes out clean.
Leave in the pan for 5 minutes then transfer to a cooling rack and let cool completely before frosting.