Tear up the 2 slices rye bread into small pieces, add the 2 T. milk and spices. Mash well, then mix with the hamburger, form into 4 patties, forming into the shape of the bread. Poke a hole in the center to prevent plumping.
In a large skillet melt 2 T. butter, add two patties and brown on one side only. Remove from pan and brown the other two.
Drain the fat reserving one teaspoon. put in the onions in the skillet and brown lightly, 8-10 minutes.
Lay the patties raw side down on the onions. Reduce the heat and cook for approximately 5 minutes.
Remove every thing, wipe out the pan.
Butter the bread, (or just put butter in the pan).
On 4 slices of bread, put 1/4 cup cheese, put a patty on, put another 1/4 cup cheese on top, and a big pile of onions. Top with the other 4 slices.
Two at a time grill each sandwich. keeping the already done ones warm in a low oven.