Cook pasta al dente, drain. Whisk together milk and egg and mix w/ hot pasta. Spread mixture in buttered 9 X 13 inch baking dish. While pasta is baking, cook pork, beef, onion and garlic in large skillet for 6 minutes over medium heat, until meat is cooked through. Drain excess fat. Stir oregano, salt and pepper in and cook 2 min. Stir in tomato sauce and cook 2 minutes. Remove pasta from oven and spread over pasta in baking dish. Sprinkle both cheeses over the top. Bake in lower 1/3 oven for 10 minutes until cheese is melted and casserole is bubbly. Let stand 5 minutes, and then cut into squares.