Slow-cooker Shredded Pork

This is a simple way to cook a Boston butt. I will make one, divide the meat in one-meal portions, and put in the freezer. Then whenever we want loaded baked potatoes, nachos, or whatever, I pull out a bag and thaw. Dinner is ready in a snap!
2 onions, cut into thick slices
1 Boston butt
Salt and pepper
1 can chipotles in adobo sauce
1 bottle beer

1. Line the bottom of the slow-cooker with onion slices. Place the pork on top of onions; sprinkle liberally with salt and pepper. Put chipotles over top of meat, and pour in beer. Cover with lid, and cook on LOW for 8 hours or until meat is done and tender.
2. Allow to cool slightly. Remove bone, and shred meat. Divide evenly among zip-top plastic bags, and freeze.