With the whey you have from making mozzarella, you can make ricotta cheese. The kit that we'd used for instructions didn't have the recipe for ricotta from whey so I used the recipe found at instructables.com and combined it with another recipe. Basically, you heat up the whey to about 200 degrees. Then you let it cool down to about 140.
Put a piece of cheesecloth or a reusable coffee strainer into your colander and pour it in.
Let it drain for 15 minutes or so, then, if you're using cheesecloth, gather up the ends and twist everything down to one end.
Don't twist too hard too quickly, or you'll squeeze your cheese out. Let it drain for another 30-60 minutes, tightening the twist slightly every ten minutes or so. (If you're using a coffee filter, just leave it sit for 30-60 minutes) Voila! You've got ricotta cheese.
It's smooth, creamy and delicate. Store it in an airtight container in your fridge.
You still will have leftover whey, but there's still more use for the whey.
You can use the whey as you would water in your baking recipes (I use the whey from our yogurt to make our bread). You can use it to mix into smoothies. You can use it to water your plants and give them a nutritional boost. You can boil it down to make MORE cheese.
I had too much whey to use just for baking and I refused to toss it. I found this recipe to make gjetost (sounds like "yea - toast"). You reduce down your whey to about 1/4 of what it was before you started boiling. Start by boiling and then just put it on a simmer till it reduces the volume. When it starts to become viscous, stir regularly. When it starts to resemble a fudge texture, stir vigorously, then put it in a buttered pan that had been frozen in the freezer. That will cool it down quickly so that it doesn't get grainy. Slice it up and eat it on crackers. I haven't tasted it yet, though I'm hoping it's good.
(Note: Our gjetost didn't get viscous, no matter how much we reduced it, so we put it in a jar to use in bread [still not gonna waste it!]. We figure there just wasn't enough protein left to solidify. Oh, well. Maybe next time.)