Chocolate cupcakes finished with a sugar glaze and piped chocolate web makes an excellent Halloween party dessert, and when arranged in concentric circles, doubles as a stunning centerpiece.
Preheat oven to 350 degrees. Whisk together flour, cocoa powder, granulated sugar, baking soda, baking powder, and salt in a bowl. Add eggs, buttermilk, oil, vanilla, and water; whisk until smooth.
Divide batter evenly among paper-lined standard muffin tins. Bake, rotating tins halfway through, until a tester inserted in centers comes out clean, about 16 minutes. Let cupcakes cool in tins on wire racks 10 minutes. Turn out onto racks and let cool completely. Cupcakes can be stored at room temperature up to 2 days before glazing and decorating.
Whisk together confectioners' sugar and milk until smooth (glaze will be very thick). Spread onto cupcakes and let stand until glaze is set. Place cupcakes on a doily or serving platter in tight concentric circles.
Place melted chocolate in a parchment cone or resealable plastic bag with a tiny hole snipped in one corner. Pipe a straight line from middle of top row of cupcakes to bottom. Pipe a second line going across middle of cupcakes, from left to right. Pipe 6 more lines through center point, spaced evenly apart; lines should form 16 even wedges. Create a web pattern by piping slightly curved, swooping lines to connect spokes, starting from center, letting chocolate flow between cupcakes.