Rosemary's Carbonara

Melt margerine in a frying pan--about 1/2 stick.
Saute 1-2 onions sliced on med till soft.
Add cubes of ham and heat.
Sprinkle flour over--about 3 tablespoons.
Pour in milk--I have never measured, just cover what you have in the pan with milk.
Heat till it boils.
If the sauce is too think, add a little more milk.
Add a jar of alfredo sauce.