Heat oven to 350° F. Grease or spray dish with Pam. Make a cheese sandwich for each person you want to serve. Use mayonnaise and mustard on them. Cut sandwiches into 4 pieces. Place the pieces in the bottom of casserole dish and cut up 3 hot dogs. Push the pieces down in dish. 
Mix milk, eggs, salt & pepper. Pour over sandwich pieces and hot dog pieces and bake 1 hour.