Weigh out ingredients
You'll need cake flour, sugar, baking powder, salt, butter, oil, milk, greek yogurt, vanilla extract, egg white.
Make the batter
Mix together dry ingredients and cubes of butter. Mix in all wet ingredients until just combined. Fold in whipped egg whites.
Fill the cupcake liners about ⅔ of the way full. Bake for 16-18 minutes or until a tooth pick inserted comes out clean.
Cool on wire rack
Allow the cupcakes to cool on a wire rack completely while you make the frosting.
Make the buttercream
Whisk together egg whites and sugar syrup. Add butter, melted chocolate, vanilla, and salt. Frost the cupcakes as desired and top with confetti rainbow sprinkles. Enjoy!
Decorate the cupcakes as desired and enjoy!