Preheat your oven to 350°F (175°C) and line a muffin tin with cupcake liners. Cream together 1 cup of softened unsalted butter and 2 cups of granulated sugar until light and fluffy, about 3 to 5 minutes. Gradually add in 4 large eggs, one at a time, incorporating each fully before adding the next. In a separate bowl, whisk the dry ingredients and set aside.

Slowly add the dry mixture to the creamed butter and sugar, alternating with 1 cup of sour cream and 1 cup of buttermilk. Start and end with dry ingredients, mixing until just combined.

In a separate bowl, mix 1 cup of prepared batter with 1/4 cup of cocoa powder. Divide the remaining batter into three bowls: leave one plain, dye one red, and the other blue using gel food coloring.

Layer the colored batters into the cupcake liners with a spoon or piping bag, starting with white, then red and blue in alternating layers, swirling gently with a toothpick.

Bake for 18 to 20 minutes, or until a toothpick inserted into the center comes out clean. The tops should be lightly golden.

Remove from the oven and let cool in the tin for about 5 minutes, then transfer to a wire rack to cool completely.

Once cool, frost with vanilla buttercream. Optionally, use cream cheese frosting and decorate with sprinkles or edible stars.