Preheat oven to 375°F (190°C).

Bring a large pot of salted water to a boil. Carefully add the cabbage leaves and boil for 5-7 minutes, or until pliable. Drain and set aside. Trim any thick ribs from the leaves.

In a large bowl, combine the ground beef, cooked rice, chopped onion, egg, salt, and pepper. Mix well.

To assemble the rolls, place about 1/4 cup of the meat mixture onto each cabbage leaf. Fold in the sides and roll up tightly.

In a 9x13 inch baking dish, combine the crushed tomatoes, tomato sauce, water, brown sugar (if using), and paprika. Stir to combine.

Arrange the stuffed cabbage rolls seam-side down in the baking dish, nestled in the sauce.

Cover the dish with foil and bake for 45 minutes. Remove the foil and bake for another 15 minutes, or until the rolls are heated through and the sauce is bubbly.

Let stand for a few minutes before serving.