Very important, roast the garlic, otherwise the fresh garlic will be too powerful.
To roast garlic:
Take loose skin off the garlic bulb and cut off the tip of the garlic cloves, still in the bulb. Rub a garlic bulb with a little bit of olive oil and wrap it in aluminum foil. Preheat the oven to 400 F / 204 C, place wrapped garlic on a baking sheet and bake for 30-35 minutes, depending on the size of the garlic bulb. (This can be made the day before and you can just refrigerate roasted garlic until ready to use.)
Preheat the oven to 350F / 180C and rub the casserole dish with some olive oil.
In a large mixing bowl, combine ground beef, ground pork, egg, bread crumbs, minced onion, minced rosemary, Worcestershire sauce, salt and pepper. Carefully peel roasted garlic and take out the roasted garlic cloves. Add them to the bowl. Mix very well, until all ingredients are completely incorporated.
Roll about 1.5 inch meatballs and place them snugly in the casserole dish. Very easy way to make equal sized meat balls, is to add mince to the palm of your hand, press down like a patty, then roll.
Stick individual, raw garlic cloves in between meatballs and add rosemary springs on top.
Cover the casserole dish with aluminum foil and bake for 35 minutes.
Take off the foil and bake for another 10-15 minutes. Remove from the oven and check if the mince is cooked.