Cook pasta according to package directions, omitting salt and fat; drain.
While pasta cooks, heat oil in a large skillet over medium heat. Add onion, thyme, red pepper, and garlic; cook until onion is golden brown (about 6 minutes). Stir in undrained clams; bring to a boil. Add pasta to pan. Combine milk and egg in a small bowl; stir well with a whisk. Add milk mixture to pan; stir well. Cook over low heat 5 minutes until milk mixture is thick, stirring constantly (do not boil). Sprinkle mixture with cheese and parsley. Serve immediately.