Grainy hot fudge is probably one of the most common problems I see with homemade recipes. u003cstrongu003eTypically, this comes from not fully dissolving the sugar in your sauce.u003c/strongu003e That's why that early cooking phase before the melted chocolate is added is so important!u003cbr/u003eu003cbr/u003eSometimes your sauce can re-crystallize u003cemu003e(in other words, form new sugar crystals from sugar that was previously melted)u003c/emu003e, in which case I recommend re-heating your fudge on the stove again, over low heat. Constantly stir the fudge and leave it on the heat until you see the sugar crystals dissolve back into the mixture which will smooth out, and your hot fudge should be good as new!