Step 1: Preheat your oven to 375°F (190°C). Lightly spray a 9x13 inch baking dish with non-stick cooking spray.
Step 2: Unroll one can of crescent roll dough. Carefully place it into the bottom of the prepared baking dish, pressing the seams together to form a solid crust that covers the entire bottom.
Step 3: Spread half of the Thousand Island dressing evenly over the crescent roll dough. Sprinkle half of the shredded Swiss cheese over the dressing.
Step 4: Evenly distribute the chopped corned beef over the layer of cheese.
Step 5: Spread the very well-drained sauerkraut over the corned beef. Ensure the sauerkraut is as dry as possible to prevent a soggy crust.
Step 6: Sprinkle the remaining shredded Swiss cheese over the sauerkraut layer.
Step 7: Unroll the second can of crescent roll dough and carefully place it over the filling, gently stretching it to cover the entire dish. Pinch and seal the edges of the top and bottom dough layers together to enclose the filling.
Step 8: Brush the top layer of crescent dough with the melted butter.
Step 9: Bake for 25-30 minutes, or until the crescent rolls are golden brown and the cheese is bubbly. If the top starts browning too quickly, you can loosely tent it with aluminum foil.
Step 10: Remove from the oven and let the Reuben Crescent Bake rest for 5-10 minutes before slicing into squares and serving. Offer additional Thousand Island dressing on the side for dipping, if desired.