Heat oil in skillet over medium heat. Add onion and saute for a few minutes until soft. Add ground beef and brown. Drain fat and return skillet to heat, add taco seasoning 1/4 cup salsa (you can use more salsa if you like.).
While the beef is cooking, prepare the other ingredients: Preheat the oven to 350*F; Grease your 9 x13 glass baking dish; cut the corn tortillas in half; and open all the canned beans.
After the beef is done, layer the corn tortilla halves around your baking dish. I put two on each long side, one on each short side, and three in the center - it is ok if there are a few gaps. Spread the ground beef over top of the tortillas.
Make another layer of tortilla halves, followed by the remaining salsa. (If you want to omit most of the tomatoes you could substitute 2 sauted onions and 1/2 cup salsa on this layer.).
Add another layer of tortillas halves, and then a layer of black beans. I drained the beans but left a little liquid. If you want a finer layer you can pulse them in your food processor.
Add another layer of tortilla halves, followed by the cooking creme (see the description for a substitution.) Sprinkle 1 1/2 cups of cheese over the cooking creme.
Add a final layer of tortilla halves. Spread the refried beans over the top of the dish, and coat with remaining cheese.
Bake at 350*F for 25-30 minutes until the cheese is golden and bubbly. Allow the dish to set for 5 minutes before serving. Serve with a large dollop of sour cream and sprinkle with diced tomato and sliced olives.
I serve this as a meal by itself - you could certainly add rice, corn, or chips as a side dish if desired.