Mix sugar and cocoa in a saucepan, stirring it with no heat until the sugar and cocoa are fully combined. Turn the stove burner to MEDIUM, not HIGH, then add a stick of butter that you’ve cut in pieces, and the can of evaporated milk, and stir with a wooden spoon until the mixture starts boiling. Stir continuously for 7 minutes (use a timer) then remove from heat and add vanilla, then stir the mix continuously for 3 minutes, beating it quickly with your spoon. Pour into a buttered 8×8 baking dish to set. Great fudge in less than 20 minutes! The main thing to do is STIR CONSTANTLY! This will help dissolve the sugar so it doesn’t taste grainy!