The process for making mysost is quite easy. It should be made within three hours after draining the whey from the mozarella (while it's fresh).
How I make mysost:
Put the fresh whey in a pot on the stove and bring it just to a boil. Skim off any foam and then pour it in a crockpot. Set the crockpot on low and let it slowly cook, stirring occasionally. It will need to cook from 6-18+ hours. Towards the end, it will begin to thicken and turn a light brown. Anytime after it has begun to get thick, you should (carefully) put it in your blender and blend for a few minutes so that it does not have a grainy texture when done. Blend in batches, filling blender only half full to avoid getting burned. Return to crockpot and continue cooking on low until as thick as peanut butter or paste. Put into small canning jars with lids so you can put one in the fridge and the rest in the freezer. Cool and refrigerate or freeze. If the cheese turns grainy, you can warm it in the microwave or on the stove and stir it. If you want it milder, you can also stir in some cream while it is warm.
We prefer this to peanut butter on our toast.
(means it's good-- we both love peanut butter!)