Brown the hamburger and fry the onion till soft, add chili powder. Add the can of tomato sauce and the can of chilies, bring to a simmer. Remove from heat. In a bowl, mix the egg and sour cream and add about 1/2 cup or so of the cheese. Mix the meat mixture with the sour cream mixture, then pour that into a 9 inch square pan. Open the can of biscuits and place the biscuits on top of the meat mixture. Sprinkle remaining cheese on top. Bake in a preheated 350 degree oven for 20 min or until the biscuits are golden brown.