Slow Cooker Butter Chicken

1 Tablespoon olive oil

2 1/4 pounds boneless skinless chicken breasts

1 cup chopped onion

2 teaspoons grated fresh ginger

1 1/2 teaspoons grated garlic

1 1/2 - 2 teaspoons garam masala

1 teaspoon ground coriander

1 teaspoon cumin

1 (14 ounce) can coconut milk

1 cup chicken broth

3 tablespoons tomato paste

2 tablespoons butter - optional

2 tablespoons flour - optional

Heat oil in a medium skillet over medium high heat.  Add chicken and cook until golden brown 3 - 4 minutes per side. Transfer to 6-quart slow cooker.

Add onion to the pan cook stirring occasionally until translucent, about 4 minutes.  Stir in ginger, garlic, garam masala, cumin and cardamom; cook, stirring constantly, until fragrant, about 1 minute.

Transfer mixture to the slow cooker. Stir in coconut milk, broth and tomato paste.  Cover and cook on low until chicken is tender and cooked through, 6 to 7 hours.  Season with salt and pepper to taste

If desired the liquid can be thickened by melting the butter in a large saucepan.  Add the flour and stir until smooth.  Pour the liquid from the crockpot into the saucepan and stir until smooth.

Serve the chicken and the sauce over rice.  Serves 6.