• Preheat your oven to 350°F. Line a 12-count muffin pan with cupcake liners and lightly spray the inside of each with non-stick spray.

Make the Cupcakes:

• In a medium bowl, sift the flour, baking powder, baking soda, and salt, and set aside.
• In a large bowl, use an electric mixer to beat the softened butter until smooth and creamy. In 2-3 additions, add the granulated sugar and mix until mostly combined after each. Once all of the sugar has been added, mix until well combined, light, and fluffy.
• Add the room temperature eggs, one at a time, and mix until just combined after each. Wipe the sides of the bowl with a rubber spatula and add the vanilla extract, sour cream, and whole milk. Mix until smooth, don't overmix.
• In 2-3 additions, add the dry ingredients and mix until just combined after each. Then mix until the batter is smooth once all of the dry ingredients have been added in.
• Divide the batter evenly between three bowls. Leave the batter in one bowl white, then add red gel food coloring to the batter in the second bowl, and add blue gel food coloring to the batter in the third bowl. Use a whisk to mix in the coloring and add a little more until you're happy with the color.
• Scoop enough of each color batter into the cupcake liners until each liner is about ⅔ of the way full. Gently tap the pan on the counter to get rid of any air pockets and use a toothpick to gently swirl the batter in the liners 2-3 times, if desired.
• Bake in the preheated oven for 15 minutes. A toothpick inserted into the center should come out clean.
• Let the cupcakes cool in the pan for about 5 minutes before removing from the pan, then let them cool completely before frosting.

Make the Buttercream Frosting:

• Add the cold heavy whipping cream to a completely clean and dry medium glass bowl. Use an electric mixer to beat the cream until it's thick. About 2-3 minutes. Set aside.
• Add the softened butter to a large bowl and use an electric mixer to beat until smooth and creamy. In 3-4 additions, add the powdered sugar and mix until mostly combined after each. Add the vanilla extract, salt, and thickened cream, and mix until the frosting is completely smooth.
• Divide the frosting between three separate bowls. Dye the frosting in one bowl red, dye one blue, and leave the other white. Add the frosting into three separate piping bags. Frost the cupcakes as desired, with solid colors, or try a multicolor swirl.
• To pipe a multicolor swirl: Flatten the three bags and lay them side-by-side inside a large piping bag fitted with a 1M open star tip. Squeeze the frosting from the top down towards the tip of the bag and frost the cupcakes. Pipe a dollop of frosting in the middle of the cupcake, then pipe a counter-clockwise circle around it, and once you complete a full circle, pipe in circles working your way back to the center of the cupcake. Finish with a peak of frosting and add some red, white and blue sprinkles.