Dot Cupcakes

Preheat the oven to 350℉ (177℃). Line cupcake pans with 15 cupcake liners.
In a small mixing bowl, whisk together the cake 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 until it is smooth and creamy. Add in the egg whites, sour cream, vanilla bean paste, and vanilla extract and mix until well combined and smooth.
Add half of the flour mixture and mix on low speed until mostly combined. Add the milk and mix again until mostly incorporated, then add the remaining flour mixture and mix on low until the batter is smooth and fully combined.
Portion the cupcake batter into the cupcake liners using a large cookie scoop (⅔ full). Bake the cupcakes for 20 minutes until the cupcakes are puffed up and they bounce back when gently touched. Cool the cupcakes in the pan for 5 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, whip the room temperature unsalted butter for 5 minutes until light, pale, and creamy.
Add half of the powdered sugar and mix on the lowest speed until incorporated into the butter. Add the remaining powdered sugar and continue mixing on low until smooth and fully combined.
Add the heavy cream, vanilla bean paste, vanilla extract, and salt, then mix on low speed until smooth and fully combined. Scrape down the sides and bottom of the bowl to ensure everything is evenly incorporated.
Increase the mixer speed to medium and whip the buttercream for about 2 to 3 minutes until it is smooth and creamy. Then, turn the mixer to low speed and mix the buttercream for several minutes to remove air bubbles.
Optional: To smooth out the buttercream, melt ½ cup of the frosting in the microwave for 15 seconds. Pour the melted frosting back into the mixing bowl and mix the frosting on low speed until the buttercream is super smooth and creamy.

Fill a piping bag fitted with a Wilton 1A piping tip with the vanilla bean buttercream frosting. Pipe a generous swirl of the frosting onto the cooled cupcakes.
Pour the rainbow nonpareil sprinkles into a small bowl. Turn each cupcake upside down and gently press the buttercream into the sprinkles, rotating until fully coated. Repeat with the remaining cupcakes.

Storing & Serving:

Room temperature: Store the cupcakes in an airtight container at room temperature for 1 to 2 days.
Refrigerator: Store the cupcakes in an airtight container in the refrigerator for 2 to 3 days. Serve at room temperature for the best taste and texture.

Note: Metric conversions and nutritional information are calculated automatically. I cannot guarantee the accuracy of this information.