In a large bowl, combine all the meatball ingredients.
Mix until blended, cover the mixture with plastic wrap, making sure to touch the surface to prevent it from drying out, and chill for 2 hours.
Preheat oven to 425ºF and line a large baking sheet with foil that has been lightly greased; set aside.
Form meat into 2-inch balls and place them on the prepared baking sheet.
Transfer to the preheated oven and bake for 40 minutes, flipping them over halfway through cooking.
Remove from the heat and set aside.
In a large pot, add butter and when it sizzles, add mushrooms and stir to coat; season with salt and pepper.
Cover and cook for 5 minutes.
Remove the lid and cook the mushrooms until the liquid is evaporated, about 15 minutes, stirring often.
Add pressed garlic and sauté for 1 minute.
Pour in cooking sherry, chicken broth and heavy cream; season with Italian seasoning and hot paprika. Stir well, bring the mixture to a boil, reduce to medium and let it simmer for 10 minutes.
Add cornstarch mixture and stir until the sauce thickens, about 45 seconds.
Put half the meatballs in the sauce and gently cover them with the sauce before adding the remaining meatballs; spoon the sauce over.
Stir in fresh chopped parsley and serve over spaghetti.