I work at BK and know how its made. the only way you can get the right taste is to find a place that sells shake mix. i dont think melting ice cream is going to give you the right taste to it. if your trying that method, best bet would be to buy a vanilla shake from BK and let is set for a while so its not so frozen, but dont let it melt. we keep the shake mix in a walk in cooler and then when used in the mocha it goes in a another cooler. mocha joes are 1/2 coffee chilled in the cooler, 1/2 shake mix, and 12 pumps of chocolate syrup. hope i kinda helped u.