Preheat oven to 350°F (180°C).
Line 3 muffin tins with cupcake liners.
Combine flour, cocoa, sugar, baking powder, salt, and pudding mix in a large bowl. Add in eggs and butter to this flour mixture, beating until smooth.
Carefully add melted butter and vanilla to the flour mixture, mixing on medium speed until smooth.
Add buttermilk to batter, mix until well incorporated and smooth.
Use food colouring to tint batter black.
Divide batter among prepared muffin pans. Bake until knife inserted into center of batter comes out clean - about 20-22 mins .
For best results, allow cupcakes to cool to cool to room temperature, before decorating. You can use a wire rack if you like.
Prepare either Swiss meringue buttercream or American buttercream, following the applicable recipe.
Once the frosting has come together, add cocoa powder. Beating to combine. Add a copious amount of black gel food coloring, mix until fully combined.
Frost your cupcake as desired, enjoy!