Preheat your oven to 350°F and lightly grease a 9x13-inch baking dish with cooking spray.
Add the bread cubes into a large bowl.
In a separate small bowl, mix the melted butter and garlic powder. Evenly pour the butter mixture over the bread cubes and mix until lightly coated (they shouldn’t be too wet or they’ll get soggy).
Layer half of the rye bread cubes in the bottom of the prepared baking dish.
Then layer the corned beef, sauerkraut, dill pickles, parsley, then salt and pepper to taste.
Evenly drizzle the Thousand Island dressing, then cover with the Swiss cheese. Top with the remaining bread cubes.
Bake the Reuben casserole in the oven for 20-25 minutes, or until the bread cubes are a light golden brown and the cheese is melted.
Let the casserole cool for a few minutes, then slice, serve and enjoy!
