Preheat oven to 375 degrees F (190° C).
Rinse quinoa and add to a small sauce pan with broth. Bring to a boil, cover and reduce heat to low. Let simmer for 15 minutes. Turn off heat and let sit for 3-4 minutes before removing lid. Do not let quinoa sit longer while covered or it will get mushy.
Heat a large pot of salted water separately over high heat to bring to a boil. Add whole head of cabbage, cover and reduce heat to low. Boil cabbage for 7-8 minutes, rolling it over while cooking to make sure all sides are submerged for at least a few minutes. Remove cabbage from pot and let cool in a strainer.
While quinoa and cabbage are cooking, heat oil over medium-high heat in a large skillet. Add onion and carrot and sauté for 3-4 minutes to soften.
Add garlic and sauté a minute longer before adding turkey. Cook turkey for 6-7 minutes until fully cooked. While cooking, use a spatula to break the turkey up into small pieces. You do NOT want large pieces of turkey, only small crumbles or you can get bites that are bland.
While turkey cooks, add Worcestershire, salt, pepper, paprika, and 1/2 cup of the marinara sauce. Add cooked quinoa to turkey mixture and stir to combine. Taste and adjust seasoning levels if desired. Remove from heat, add the egg and stir to mix in.
Spoon about 1/2 cup of the marinara sauce into the bottom of an empty 9 X 13" casserole dish and spread out to a thin layer.
Peel leaves from cabbage carefully to keep them intact. Scoop 1/2 - 3/4 cup turkey filling into the center of a cabbage leaf. Fold the bottom half over the filling and then tuck the sides in. Fold the upper half over and lay seam side down in the prepared casserole dish. Repeat with remaining cabbage leaves until dish is full and filling is gone (typically 10 rolls).
Spread remaining marinara sauce on top of cabbage rolls and bake for approximately 30 minutes until cabbage is fully cooked.
Garnish with fresh herbs and serve with sour cream or plain yogurt.