I've never tried making carbonara with white sauce - it's usually tagliatelli, ham or crispy bacon, eggs, cream and parmesan. Chuck the ham/crispy bacon and cooked spaghetti/tagliatelli in a warm pan, stir in the beaten eggs and cream until eggs are cooked but still glossy, sprinkle parmesan and black pepper over the lot and serve on warm plates if you can be bothered - otherwise eat out of the pan (saves on washing up).
Choc and cranberry rolls went down a treat - the recipe will be entered in the book I'm compiling for the grand-daughters.