Preheat oven to 350F (175C) and prepare a 12 count muffin tin* (see recipe note) with paper liners. Set aside.
2.Place butter in the bowl of a stand mixer (or you may use a large bowl and an electric hand mixer) and beat until smooth and creamy.
3.Add sugar and oil and beat again until ingredients are very well-combined, smooth, and creamy.
4.Scrape down the sides and bottom of the bowl and then stir in your vanilla extract.
5.In a separate bowl, whisk together your flour, baking powder, and salt.
6.With mixer on low speed, gradually alternate between adding the flour mixture and your buttermilk to the butter mixture, starting and ending with the flour mixture. Stir until each one is almost completely combined before adding the next. Be sure to scrape the sides and
7.bottom of the bowl so that all ingredients are combined.
8.In separate, completely clean and grease-free bowl, combine your egg whites and, with a hand-mixer on high-speed, beat until stiff peaks form.
9.Using a spatula, gently fold your egg whites and sprinkles into your batter. Take care to scrape the sides and bottom of the bowl so that ingredients are well-combined, and take care not to over-mix.
10.Divide batter into prepared cupcake tin, filling each liner 3/4 of the way full.
11.ake on 350F (175C) for 18 minutes, or until a toothpick inserted in the center comes out mostly clean with moist crumbs (not wet batter). For mini cupcakes, bake 14-15 minutes.
Allow cupcakes to cool completely before frosting.