Pre-heat oven to 400 degrees.
Place meat in a mixing bowl and season with ¼ tsp salt and ¼ tsp pepper. Add in garlic, egg and additional egg yolk, parmesan, bread crumbs, and minced sage.
Roll into 8 large meatballs and arrange in a large baking dish. Coat the meatballs with 2 Tbsp extra-virgin olive oil.
Use a wooden spoon to make an indentation halfway into the meatball and fill the cavity with gorgonzola cheese.
Bake meatballs for 15-20 minutes, until they’re golden brown and cooked through.
While meatballs are cooking, make the tomato sauce. Heat remaining 1 Tbsp extra-virgin olive oil and butter in medium saucepan over medium heat and add bay leave and onion. Season with remaining ¼ tsp salt and ¼ tsp pepper.
Add chicken stock and tomatoes and heat through. Stir in the cream, reduce heat to medium-low, and simmer for about 10 minutes to thicken slightly.
Spoon sauce into shallow bowls and top with meatballs. Sprinkle with additional parmesan cheese.