Combine the chopped onion, dry bread crumbs, milk and galic powder in a bowl. Set aside until the milk is almost completely absorbed. Add the egg and the hamburger and mix well(this works best using your hands, like when making meatloaf). Dump this mixture into a greased casserole dish or really deep pie plate. Form the hamburger mixture into a "crust" with a hollow in the center. Be sure to work the mixture up the side of the dish.
In another bowl, mix the rice and the pasta sauce. Pour this into the hollow and top the rice mixture with the cheese. Bake 40 to 60 minutes.
***Put something to catch drips/splatters under this one--it always seems to drip onto the bottom of the oven. Putting the casserole dish on a pizza pan covered with aluminum foil works great.