Easy butter-get the cream separated from milk and put cream in a tight sealing canister(mason jar with lid is great). Wrap in a towel just in case it leaks and shake, shake, shake. And shake some more. Pass it around the family shaking until it gets lumped up and butter consistency. Heresy usually still some fluid that you have to drain. It takes a while, but its pretty easy to do. We then form little logs with the butter and wrap in wax paper, but you could throw it in a tupperware just as easy. Obviously refrigerate.
Our UPS guy's mom has 2 cows(don't know what kind) that they milk and she does all that stuff, and uses the whole milk and cream for cakes...they are the best cakes ever! You say you have a Gilbert cake and anyone in the county knows what you're talking about. They are about 1/3 the price of a store cake and about 10 times better! Had one for grad party and people wondered why we cut pieces so small till they tried it and found how rich it is. A 2"x2" piece is about all you can do they are so good.