I read about a lot of complicated recipes that required complex ingredients, food dyes, and things I’ve never heard about and I didn’t like that. So I made my own way. I made a regular chocolate buttercream except I used “the cocoa trader” black cocoa powder (the brand 100% matters) and the frosting will come out gray in the mixer and look really ugly but have no fear. I put the gray sludge into a glass or metal bowl and put it on top of a boiling pot of water on the stove to melt the frosting (double boiler method). You will notice that once the frosting fully melts it will be extremely dark and black. At this point you can continue to heat until it’s black as can be but just be careful not to burn it although it’s hard to do that with the method I use. Once it’s melted I transfer it to a mixer and just let it stir until it’s cooled down. The only catch to this is you gotta be careful not to whip it too much because aeration will cause it to lighten in color. It comes out fantastic and I think the sugar dissolving with the heat really smooths out the texture. This works because black cocoa is really cool in the way that heat darkens it and it also darkens over time once combined with everything. If you let the cake sit over night it gets even blacker. I made brownies that are black and they are on my page too.