Slow Cooker Butter Chicken

Ingredients (16)

• 3 pounds large boneless-skinless chicken breasts (5 to 6)
• 1 cup onion diced (1 small onion)
• 4 tablespoons unsalted butter
• 1 tablespoon minced garlic
• 1 tablespoon grated ginger
• 21/2 teaspoons curry powder
• 2 teaspoons chili powder
• 2 teaspoons garam masala
• 1/2 teaspoon cumin
• 1/2 teaspoon salt
• 1 cup tomato sauce
• 11/4 cups heavy cream room temperature and divided
• 6 tablespoons tomato paste
• 2 tablespoon cornstarch
• 4 cups cooked jasmine rice according to package directions
• fresh cilantro for garnish