Preheat oven to 350°. Grease a small baking sheet with cooking spray.
Unroll 1 tube of crescent rolls onto pan and pinch seams together. Bake
until lightly golden, 10 minutes.
Layer corned beef, swiss, and then sauerkraut on top of par-baked
crescents. Top with second tube of crescent rolls and pinch seams and
sides together. Brush with butter and sprinkle with salt and caraway
seeds.
Bake until golden and dough is cooked through, 30 minutes more.
Meanwhile, make Russian dressing: In a medium bowl, combine mayonnaise,
ketchup, horseradish, worcestershire sauce, sugar, and paprika. Season
with salt and pepper.
Cut Reuben into squares and serve with Russian dressing for dipping.