Place cabbage on the cutting board with core facing up. Remove core and center of cabbage, leaving a 1-in. shell.
In a large bowl, combine the ground meat, minced toast, minced onion and an egg. Seasoning with salt, pepper and nutmeg. Mix well.
Spoon mixture into cabbage shell. Place cabbage on a baking sheet or plate.
Bake at 400°F (200°C) for 15 minutes.
In a large skillet over mid-high heat, adding olive oil, chopped carrots, chopped onion, chopped parsnips, garlic, and leeks. Stir in tomato paste and red wine. Seasoning with salt and pepper. Add 1/2 cup water and bring to a boil.
In a cooking pot, carefully add stuffed cabbage and the sauce. Cover the pot and transfer to oven. Bake at 365°F (185°C) for 45 minutes, until whole cabbage is tender and a thermometer inserted in the middle of the cabbage reads 165°F / 75°C. Then, place cabbage on a serving platter; keep warm.
In a small bowl, combine equal parts cornstarch and cold water. Stir together until smooth. Pour cornstarch mixture into the sauce and cook over medium heat, stirring continually, until the sauce reaches your desired consistency.
Baste the thicken sauce over the stuffed cabbage. Enjoy!