Mix the breadcrumbs with the half and half in a large bowl.
Grind or grate the cheese.
Finely chop the parsley.
Cut the onion into a small dice. You could use a food processor, or grate the onion with a coarse grater.
Combine all ingredients in the bowl with the breadcrumb mixture. Mix well, and be sure there are no pockets of any ingredient.
Cook
On a large cutting board, divide the meat mixture into three equal parts. Shape one of the meat thirds into a log about two inches wide. Cut each log into eight equal pieces. Roll each piece in your hands to make a meatball, and place the meatballs on the prepared baking sheet. Repeat for each third.
Bake until the meatballs are lightly browned, and the internal temperature is 165℉. This will take about 30 minutes.