So, in case you read this post and give in to the temptation to make your own, I'll save you a little hassle and let you know how much of what worked for me. :) And I'll tell you this, too, it's VERY sweet. A little goes a looooong way. And it's not exactly a health food--I told you it's candy, right? So don't judge.
As I said, you take a very small potato and cook it (I microwaved it) so that you can mash it (without the skin). Then mash it with about a tablespoon of milk. Gradually add almost a pound of powdered sugar. Yes, I said almost a POUND. I used a pound, and it was just slightly difficult to mold. Then you work that into a dough, and split it in half. Then roll each ball to about 1/4-inch thickness. A trick that I used is to roll it between two sheets of parchment paper. Works like a charm, and then I didn't have to wash my rolling pin. Once you get it all spread out, slather on your peanut butter. Roll it up so that it looks something like a burrito (as Charlie said), and then slice it into your bite-size candies.
Charlie really loved making this as well as eating it. So yummy!