Preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius). Spray a 9-inch-by-11-inch pan with non-stick spray.
Thoroughly rinse and drain the sauerkraut to prevent the casserole from being soggy.
Spread half the bread cubes in the prepared pan. Layer half the pastrami over top, followed by half the sauerkraut, half the cheese, all of the pickles and all of the mustard.
Sprinkle the caraway seeds on top. Layer the remaining bread cubes, pastrami, sauerkraut, cheese and the Thousand Island dressing.
Sprinkle the rye bread crumbs on top of the casserole.
Bake for 35 to 40 minutes, until the top is browned, the center is set, and the mixture is bubbly.