Now the best part: CHEESE! I cannot stress enough to you how much better your final product will turn out if you part with a few extra pennies and buy a ball of (sort of) fresh mozzarella. In the end the shredded stuff will turn out fine, save you a step, and cost a little less but your tastebuds will love you for going the extra mile. If you went the fresh(er) route and got a hunk of cheese, now is the time to grate it. Grate to taste, but I'd suggest at least 1/2 a cup just to pull things together. You'll get better results from about 3/4 of a cup and if you want to add lots of flavor and don't care about a small amount of extra calories, throw on a whole cup.