Over high heat bring a stock pot filled ¾ full with water to a boil, add a pinch of salt and add tortellini. Cook until al dente 12 - 15 minutes. Remove tortellini with a large slotted spoon, set aside.
Place a steamer insert onto the rim of the stockpot, add Brussels sprouts and steam for 6 - 8 minutes. Place into a bowl.
Add carrots to water and cook for 10 minutes, set aside.
Pour water from stock pot and add 4 cups of chicken stock and 1 cup of water and bring to a simmer.
Add cooked tortellini, chicken, Brussels sprouts, carrots, parsley, olive oil and a sprig of rosemary. Add sea salt and fresh cracked black pepper to taste.
Allow to simmer for 20 minutes.
Serve hot sprinkled with shredded mozzarella cheese.