Preheat oven to 350 degrees. Place pie shell on cookie sheet. Set aside.

In a skillet, brown sausage until fully cooked. Drain off any excess grease. Add the green onion and cook for 1 minute longer.

Spread ½ sausage mixture in pie shell and sprinkle with ½ cheese. Spread remaining sausage in pie shell.

In a bowl, whisk together half and half, eggs, garlic salt, pepper, and ground mustard.

Pour evenly over sausage. Sprinkle with remaining cheese.

Place in oven and bake for 45-50 minutes or until the center is set when gently shaken. Check at 30 minutes and lay a piece of aluminum foil on top to prevent over browning if needed.

Allow to rest for 10 minutes. Serve warm. serves 6-8.