Preheat your oven to 350°F (175°C) and line a standard muffin tin with cupcake liners.

In a large mixing bowl, combine the flour, sugar, cocoa powder, baking powder, baking soda, and salt. Whisk until well blended.

Add the eggs, milk, vegetable oil, and vanilla extract to the dry ingredients. Beat on medium speed for 2 minutes until smooth.

Stir in the boiling water until fully combined; the batter will be thin.

Pour the batter into the prepared cupcake liners, filling each about 2/3 full.

Bake for 18-20 minutes or until a toothpick inserted in the center comes out clean. Allow the cupcakes to cool in the pan for 5 minutes, then transfer them to a wire rack to cool completely.

While the cupcakes cool, prepare the buttercream frosting. In a large bowl, beat the softened butter until creamy.

Gradually add the powdered sugar, mixing on low speed until combined.

Add the heavy cream and vanilla extract, then beat on high speed for 3 minutes until fluffy.

Divide the frosting into two bowls. Color one bowl with red food coloring and the other with blue food coloring.

Frost the cooled cupcakes with the buttercream, alternating colors for a festive look. Top with red and blue sprinkles.