How to Make It
Prepare the Cake: Preheat oven to 350°F. Beat together sugar and butter with an electric mixer on medium speed until light and fluffy, about 2 minutes. Add eggs, 1 at a time, and beat until just incorporated. Stir in vanilla.
Whisk together flour, cocoa, malted milk powder, baking soda, baking powder, and salt in a medium bowl. Add flour mixture to butter mixture in 3 batches, alternating with milk, beating on low just until all flour is incorporated.
Divide batter between 24 lined muffin cups, and bake until a toothpick inserted in the middle comes out clean, 18 to 20 minutes. Let cupcakes cool in muffin pans on wire racks, about 45 minutes.
Prepare the Frosting: Beat powdered sugar and butter with an electric mixer on medium speed until fluffy, about 3 minutes. Add heavy cream, and beat on low speed just until smooth. Add blue food coloring to reach desired color. Spread frosting on cooled cupcakes.
Stir together 2 drops brown food coloring gel and 1/8 teaspoon water in a small bowl. Dip the tip of a small, clean paint brush into mixture, and flick over the top of frosted cupcakes to create a robin egg look.