Cream together cheese and chopped onions; form into 12 walnut sized balls. Wrap half a chicken breast around each one, and one or two slices of bacon around that in such a way as to cover as much of the chicken as possible. Secure each little bundle with a toothpick or two. Then broil them on a rack, with a drip pan underneath 6 to 8 inches from the broiler unit. Turn occasionally, as they brown, and broil about 30 minutes, or until the bacon is done.