Preheat your oven to 400°.
Chop the corned beef and layer it on the bottom of a 9 x 13 in. baking dish.
Rinse and drain the sauerkraut. Pat it dry with paper towel and push the liquid out through the strainer.
Layer the sauerkraut over top of the corned beef.
Spread the dressing over top of the sauerkraut.
Layer the shredded Swiss cheese over the dressing.
Cube the rye bread and layer it on top of the Swiss cheese.
Spray the butter cubed with cooking spray or brush melted butter over the bread cubed. It helps it to toast up nicely while baking.
Bake this for 15-20 minutes or until the cheese is melted.
