01 -
Line an 8x8 pan with parchment paper.
02 -
Heat chocolate, milk, butter, salt and vanilla in a pot over low heat. Stir until smooth, about 5-7 minutes. Don't rush or it'll burn.
03 -
Take off heat and mix in black coloring until it looks like coal.
04 -
Spread in pan. Add sprinkles if using.
05 -
Let cool, then cover and chill at least 8 hours or overnight.
06 -
Lift out with parchment and cut into 1-inch squares.