How to Make It
Preheat oven to 350° F. Place paper liners in 2 12-cup muffin tins.
Make cupcakes: In a medium bowl, whisk together flour, cocoa powder, baking soda and salt. In a small bowl, whisk together buttermilk, red coloring, vinegar and vanilla. In a large bowl, using an electric mixer on medium-high speed, beat butter and sugar until fluffy, about 3 minutes. Add eggs, 1 at a time, beating well after each addition and scraping down sides of bowl. Alternate adding dry ingredients and buttermilk mixture, beginning and ending with dry ingredients. Beat until just incorporated.
Divide batter evenly among paper liners, filling each about halfway. Bake until a toothpick inserted into center of a cupcake comes out clean, about 25 minutes. Cool in pans on wire rack for 10 minutes, then remove cupcakes from pans to rack to cool completely.
Make frosting: In a large bowl, using an electric mixer on medium-high speed, beat cream cheese and butter until creamy, about 3 minutes. Beat in vanilla. Gradually beat in sugar and cocoa powder until well combined.
Spread chocolate-cream cheese frosting on cupcakes and arrange on a platter in a tight, circular formation. Use decorating gel to pipe concentric circles, starting with small circle in center and getting larger toward outer edge. Starting in center, drag a toothpick through circles, as though you were making spokes on a wheel, to complete large web design.