Mix meat, crumbs, eggs, onion, salt, pepper and thyme in bowl. Shape into 30 meatballs, using 1 tablespoon for each.
Place 15 meatballs in 13 x 9-inch microwave-safe glass baking dish. Microwave, uncovered, on high power for 8 minutes, turning once halfway through cooking. Remove and keep warm. Repeat with remaining meatballs.
Place mushrooms and butter in 13 x 9-inch microwave-safe baking dish. Loosely cover with plastic wrap. Microwave on high power 5 minutes, stirring once after 3 minutes.
Stir flour into mushrooms. Microwave, uncovered, on high power 1 minute. Stir in milk, half-and-half, granules, salt, black pepper, nutmeg, cayenne pepper and thyme. Microwave on high power 8 minutes, stirring halfway through cooking. Whisk until smooth.
Serve meatballs and mushroom sauce over noodles. Garnish with parsley if desired. Makes 6 servings.