Thanks to MIL for this one! I made some changes, so I'll give you the recipe the way I made it!
1/2 cup sour cream (I use light, as if that makes a difference. You'll see.)
1/2 cup 1,000 Island Dressing
1 pound corned beef from the deli
1 cup sauerkraut
6 slices of rye bread, cubed.
1/4 cup butter, melted
2 cups swiss cheese
Preheat oven to 350.
Use a 9x9 casserole dish. Mix up the sauerkraut with the dressing and the sour cream. Put that on the bottom of the dish. Layer the corned beef and the cheese. I added a little bit of sharp cheddar for the heck of it.
Toss the bread with the butter, cover the casserole with that.
Bake for 30 minutes, covered, then another 10-15 uncovered.
Viola! Delicious casserole.
If you can find fresh baked rye bread, use it. So few ingredients in this casserole, you'll want each one to be the best you can find.