
Preheat oven to 350F (175C) and line a 12-count cupcake tin with paper liners. Set aside.
In a large mixing bowl, combine butter and sugar and use an electric mixer to beat until lightened and well-combined.
Add oil and extracts and stir until smooth and creamy and completely combined.
In a separate, medium-sized mixing bowl, whisk together cake flour, baking powder, baking soda, and salt until well-combined.
Using a spatula, alternate adding the dry ingredients and buttermilk to the butter mixture. Start by adding about a third of the dry ingredients, gently fold into the butter mixture with a spatula, then add half the buttermilk and fold this into the batter until just combined. Repeat until all the buttermilk and flour mixture are added.
Pour egg whites until a clean, dry mixing bowl (preferably glass or metal – do not use rubber, silicone, or plastic).
Use an electric mixer to beat the egg whites until stiff peaks have formed (mixture will be thick and white and if you remove the beater from the mixture, the peaks that form should hold their shape and not fold over on themselves).
Add the whipped egg whites to the batter and use a spatula to gently fold into the mixture until about halfway combined. Add sprinkles and continue to gently fold until batter is uniform.
Evenly divide batter into prepared tin and transfer to center rack of 350F (175C) oven. Bake for 17 minutes/until a toothpick inserted in the center comes out clean or with a few moist crumbs (no wet batter).
Allow cupcakes to cool in the tin for 5-8 minutes before carefully removing to a cooling rack (I use a butter knife to gently pry them up and carefully remove them – be careful, the tin and cupcakes will still be hot!) to cool completely before frosting.