Preheat your oven to 350°F (175°C). Line a cupcake pan with cupcake liners.

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

Add the egg, milk, vegetable oil, and vanilla extract to the dry ingredients. Mix until smooth.

Carefully stir in the boiling water until fully combined. The batter will be thin.

Pour the batter into the prepared cupcake liners, filling each about two-thirds full.

Bake for 18-20 minutes or until a toothpick inserted into the center comes out clean. Let the cupcakes cool completely in the pan before transferring them to a wire rack.

While the cupcakes cool, whip the heavy cream with the powdered sugar until stiff peaks form.

Divide the whipped cream into three bowls. Leave one bowl plain, add red food coloring to the second bowl, and blue food coloring to the third bowl. Mix until the desired colors are achieved.

Once the cupcakes are cool, frost the top of each cupcake with the whipped cream. Use the plain cream for the white frosting, red for the red frosting, and blue for the blue frosting.

Decorate the top of each cupcake with halved strawberries and blueberries to create an American flag design.