Crumble the sausage into a large saucepan, and sauté over medium low heat, breaking the meat into small pieces while it cooks, do not allow it to brown or get crisp. When the meat is about three quarters cooked, add the onion and cook until the onion is transparent. Drain off all but 2 tablespoons of the meat drippings, you don't have to be too precise about this. Stir in the flour with a whisk, and cook over medium low heat for 6 to 7 minutes or until the flour turns golden and bubbles up. Pour in the milk all at once, and add the seasoning. Cook and whisk until the mixture thickens. Place at least 3 biscuit halves on each plate and top with sausage gravy. Serves 4 - 6