I make this every couple of months - but I don't use a white or cream sauce, it's more like regular brown gravy.

I brown the hamburger and at the same time put in a finely diced onion - When it's done browning, I add water to cover it all, then a "glop" or two (to your taste) of the beef base paste. I also add garlic powder. Then cover and let simmer for about 45-60" - the longer the better, the flavors blend better, and the hamburger is really tender.

Then I thicken it just before serving with cornstarch/coldwater mixture - add a little thickening at a time until it's the right consistency. Sometimes I also add any mushrooms, chopped or sliced into the mixture along with the onions.

This is something school and hospital cafeterias serve a lot over mashed potatoes. Hope this helps