Preheat your oven to 350°F.In a mixing bowl, add all the ingredients excluding the mozzarella.
Stir well to combine the ingredients fully.Prepare a ¼ cup measuring size to form the meatballs.
Stuff ½ teaspoon of cheese inside.
Completely cover the cheese with meat.Transfer the meatballs to a baking dish and bake for 15 minutes until the meat turns golden brown.
Remove from the oven and set aside.While baking, sauté the mushrooms in butter.Add a dash of salt to the cooked mushroom before turning off the heat.
Pour the Dijon mustard and cream on top.Serve the meatballs in a plate and drench them with the sauce.
Enjoy!