Start the cooking process by preheating the oven up to 350 degrees.
Put the chopped cabbage in your casserole dish. You do not need to grease the pan before.
Place the coarsely chopped sweet onion on top of the cabbage. Put some pepper and salt on the cabbage and onions.
Mix the chicken soup, butter, mayonnaise together then place it on top of the cabbage and onions. Just spread the mixture lightly without mixing it.
In a separate bowl, mix all of the topping ingredients then sprinkle them on top of the casserole dish.
Cook this meal for around 45 minutes at 350 degrees. Do not remove from the oven until the top looks golden. The casserole should be bubbly too. Ensure you keep an eye on the oven so that you do not overcook the food.