Preheat oven to 450 degrees F. In a large bowl combine egg, beef, sausage, ricotta cheese, panko, onion, the 1/2 cup Parmesan, the garlic, thyme, parsley, and salt with hands. Form mixture into forty 1-1/2-inch meatballs.
Heat an extra-large cast-iron skillet with olive oil. Brown meatballs, half at a time, in hot skillet about 10 minutes per batch. Return all meatballs to skillet. Bake for 10 minutes or until done (160 degrees F).
Spoon sauce into two small cast-iron skillets or serving dishes (cast-iron skillets can be heated or kept warm on a grill). Place baked meatballs in sauce, turning to coat. Sprinkle with chopped parsley and the 2 tablespoons Parmesan. Serve meatballs with bamboo skewers.
Domenica's Simple Tomato-Garlic Sauce
In a large saucepan cook garlic and crushed red pepper in hot oil over medium heat for 1 minute. (Do not let garlic brown, which causes it to develop a bitter taste.) Stir in tomatoes and salt. Bring sauce to boiling. Reduce heat to low. Simmer, uncovered, for 15 minutes, stirring occasionally.