To prepare the tomato-garlic sauce, in a large saucepan over medium heat, warm the olive oil. Add the garlic and red pepper flakes and cook, stirring frequently, until fragrant, about 1 minute. (Do not let the garlic brown, which will cause it to develop a bitter taste.) Stir in the tomatoes and salt and bring to a boil. Reduce the heat to low and simmer, stirring occasionally, for 15 minutes. Remove from the heat and cover to keep warm.

To prepare the meatballs, preheat the oven to 400°F. 

In a large bowl, combine the egg, ground beef, sausage, ricotta, panko, onion, the 1/2 cup Parmesan, garlic, thyme, parsley and salt and mix with your hands. Form the meat mixture into forty 1 1/2-inch meatballs.

In an extra-large cast-iron skillet, warm some olive oil. Working in 2 batches, add the meatballs and brown on all sides, about 10 minutes per batch. Return all the meatballs to the skillet, transfer to the oven and bake until an instant-read thermometer inserted into the center of a meatball registers 160°F, about 10 minutes.

Spoon the tomato-garlic sauce into 2 small cast-iron skillets or serving dishes (cast-iron skillets can be heated or kept warm on a grill). Place the baked meatballs in the sauce, turning to coat. Sprinkle with parsley and the 2 tablespoons Parmesan. Serve the meatballs with bamboo skewers.