Slow Cooker Butter Chicken

I love Indian food, but it's not very available where I live.  This recipe was awesome and I'm going to try to make more Indian dishes.

Slow Cooker Butter Chicken
from Salu-Salo

2 onions, diced
3 cloves garlic, minced
3 tbsp butter
2 tbsp grated fresh ginger
2 tbsp packed brown sugar
2 tsp chili powder
3/4 tsp ground coriander
3/4 tsp ground turmeric
1/2 tsp cinnamon
1/2 tsp ground cumin
1/2 tsp salt
1/2 tsp pepper
1 28 oz. can diced tomatoes
1 cup chicken broth
1/4 cup almond butter or cashew butter
3 lbs boneless, skinless chicken thighs
1 cup sour cream

In slow cooker, combine onions, garlic, butter, ginger, brown sugar, chili powder, coriander, turmeric, cinnamon, cumin, salt, pepper and tomatoes.  In a small bowl, whisk broth with almond butter; pour into slow cooker.  Mix everything together.  Cover and cook on low for 5-8 hours.  With an immersion blender, puree sauce until smooth.  Add chicken; cook over high until juices run clear when chicken is pierced, about 50-60 minutes.  Stir in sour cream and serve.