Yellow Cupcakes

Preheat the oven to 350℉ (177℃). Line a cupcake pan with 12 cupcake liners.
In a medium mixing bowl, whisk together the all-purpose flour, baking powder, and salt. Set aside.
In the bowl of a stand mixer fitted with a paddle attachment or in a large mixing bowl with an electric hand mixer, cream the granulated sugar, unsalted butter, and vegetable oil for a few minutes until light and creamy. Add the egg, egg yolks, sour cream, and vanilla extract and mix until smooth.
Add in half of the flour mixture and mix until mostly combined. Then, pour in the milk and mix. Add the remaining half of the flour mixture and mix until combined and smooth.
Portion the cupcake batter into the cupcake liners using a large cookie scoop about ¾ full. Bake the cupcakes for 20 minutes or until the cupcakes bounces back when gently touched. Cool the cupcakes in the pan for 2 minutes and then transfer to a wire rack to cool completely.

In the bowl of a stand mixer fitted with a paddle attachment or in a large mixing bowl with an electric hand mixer, cream the unsalted butter for 5 minutes until smooth and creamy.
Add in the powdered sugar and mix on low speed until fully combined with the butter. Add in the dark cocoa powder, vanilla extract and salt. Mix until the ingredients are well combined. Drizzle in the heavy cream while mixing on low speed.
Turn the mixer to medium speed and whip the buttercream for 2 to 3 minutes until it is smooth and creamy. Mix the frosting on low speed for several minutes to remove any air bubbles.

Fill a piping bag fitted with a Wilton 1M piping tip with the chocolate buttercream frosting. Pipe a generous swirl of chocolate frosting onto the yellow cupcakes. Decorate the cupcakes with rainbow sprinkles.

Store the cupcakes in an airtight container at room temperature for 1 to 2 days or in the refrigerator for 2 to 3 days. Serve at room temperature.

Metric conversions are calculated automatically. I cannot guarantee the accuracy of this information.