In a medium saucepan, sauté the sliced onions in the olive oil until golden brown. Add the garlic and cook for 30 seconds. Add the milk and the Francesco Rinaldi® Classic Alfredo Sauce to the pan and allow the sauce to come to a simmer. Add the cheeses and the cayenne pepper. Adjust the seasoning with salt and pepper. Stir in the penne and fresh rosemary and place into a glass or ceramic baking dish.