In a large stockpot or Dutch oven, melt butter over medium-high heat.
Add onion and garlic; cook, stirring frequently, until lightly browned; about 10 minutes.
Add flour and cook, stirring constantly, for 2 minutes.
Add chicken broth and next 6 ingredients.
Bring to a boil; reduce heat; simmer for 2 minutes or until slightly thickened.
Add cheese, 1 cup at a time, stirring until cheese melts between each addition.
Stir in cream and turkey; cook until heated through; about 2 minutes.
Garnish servings with cilantro and onion, if desired.