Preheat the oven to 350°F (175°C).
Bring a large pot of water to a boil. Carefully core the cabbage and separate the leaves. Blanch the cabbage leaves in boiling water for 2-3 minutes until pliable. Drain and set aside to cool.
In a large bowl, combine the ground beef, cooked rice, chopped onion, minced garlic, egg, salt, black pepper, paprika, and dried thyme. Mix thoroughly until well combined.
Place a cabbage leaf flat on a clean surface. Trim the thick vein at the base if necessary to make rolling easier.
Spoon about 2-3 tablespoons of the meat mixture onto the center of the leaf. Fold the sides over the filling and roll tightly from the base to the tip, enclosing the filling completely. Repeat with remaining leaves and filling.
In a large ovenproof baking dish, heat olive oil over medium heat. Pour in the tomato sauce and beef broth, stirring to combine. Add lemon juice and season with a pinch of salt and pepper.
Arrange the cabbage rolls seam side down in the baking dish, packing them snugly together.
Cover the dish tightly with aluminum foil and bake in the preheated oven for 1 hour.
Remove the foil and bake for an additional 15 minutes to allow the tops to brown slightly.
Remove from oven and let rest for 10 minutes before serving.