Fill a large pot with water and bring it to a boil. Add the cabbage to the boiling water and cook it for 5 to 7 minutes, until slightly tender. I prefer it to have a little crunch, but you can cook it longer if a softer texture is desired. Drain the cabbage in a colander, rinse with cold water and set aside.
In the same large pot, warm the olive oil over medium-low heat. Add the onion, carrots, and garlic, and cook for 5 minutes, or until softened. Add the mushrooms, sprinkle with salt & pepper, and continue to cook for 5 more minutes, until the mushrooms have released their juices.
Stir in the dried herbs, diced tomatoes, tomato sauce, and tomato paste, then bring to a low boil. Reduce to a simmer and cook for 10 minutes. Stir in the lentils and brown rice.
Preheat the oven to 350°F, then lightly grease a 9 x 13 casserole dish.
Use a paper towel to blot the cabbage to make sure it’s dry, then distribute half of it along the bottom of the dish and top with half of the sauce. Layer the remaining cabbage on top and finish with the remaining sauce. Top with cheese.
Place the casserole in the oven and bake for 25 minutes. Turn the oven to broil and broil for 3-5 minutes, or until the cheese is lightly browned on top. Remove from the oven and allow to cool for at least 5 minutes before serving. Top with fresh parsley and serve warm.