Creating this amazing Slow Cooker Indian Butter Chicken is simple if you follow these steps:

1. Prep Chicken: If not already done, trim any excess fat off the chicken thighs and cut them into large chunks.
2. Combine Ingredients: In your slow cooker, add the chicken pieces, diced onion, minced garlic, and ginger.
3. Add Spices: Sprinkle the garam masala, cumin, turmeric, chili powder, salt, and black pepper over the chicken mix.
4. Add Tomatoes and Butter: Pour the can of diced tomatoes over the chicken, and place the butter on top.
5. Stir: Gently give everything a stir to ensure even distribution of ingredients.
6. Cook: Cover the slow cooker with a lid, and cook on low for 6-8 hours or on high for 4-5 hours.
7. Add Cream: About 30 minutes before serving, stir in the heavy cream or coconut milk.
8. Finish Cooking: Continue cooking until heated through and the sauce is creamy.
9. Shred Chicken (optional): If you desire a shredded chicken texture, use two forks to shred the chicken directly in the slow cooker.
10. Garnish: Before serving, sprinkle fresh cilantro over the top for added flavor and presentation.

These steps will ensure you create a dish that is not only delicious but also comforting and satisfying.