Chocolate Stout Chili

Name: Chocolate Stout Chili
Ingredients: 1 tablespoon olive oil; 1 medium onion, chopped; 3 garlic cloves, minced; 2 chipotle peppers in adobo sauce, chopped; 1 1/2 tablespoons ancho chili powder; 1 teaspoon cumin; kosher salt to taste; freshly ground black pepper to taste; 2 tablespoons tomato paste; 1 28-ounce can stewed tomatoes; 1 tablespoon dark cocoa powder; 1 28-ounce can red kidney beans, drained and rinsed; 2 cups cooked beef, cut into bite-sized pieces; 1 ounce unsweetened chocolate, chopped; 1 1/2 cups chocolate stout, divided; 1/2 cup tomato puree