Heat a Dutch oven over medium-high heat. Coat pan with cooking spray. Add onion, bell pepper, garlic, and turkey to pan; sauté 8 minutes or until turkey is browned and vegetables are tender. Add sugar and next 9 ingredients (through chipotle) to pan, stirring to blend; bring to a boil. Reduce heat; simmer 15 minutes or until slightly thickened, stirring occasionally. Add chocolate, stirring to melt. Ladle 1 1/4 cups chili in each of 8 bowls; top each serving with 1 tablespoon sour cream. Garnish with green onions.