Heat 2 tablespoons of vegetable oil or ghee in a large skillet over medium heat. Add one finely chopped large onion, along with 4 cloves of minced garlic and a tablespoon of grated fresh ginger. Sauté for about 5 minutes, stirring frequently until the onion turns translucent and fragrant.

Next, stir in the spice blend for your dish by adding 2 teaspoons of garam masala, 1 teaspoon of ground cumin, 1 teaspoon of ground coriander, ½ teaspoon of turmeric, 1 teaspoon of smoked paprika, 1 teaspoon of salt, and a pinch of cayenne pepper. Cook this mixture for 2 minutes.

Now, add 2 pounds of boneless, skinless chicken thighs to the skillet, ensuring they are coated with the spiced onion mixture. Sear the chicken for about 5 minutes.

Carefully transfer the browned chicken and the spiced mixture into a large slow cooker.

Pour in a 14-ounce can of crushed tomatoes and a 14-ounce can of full-fat coconut milk. Add 2 tablespoons of tomato paste for richness, and combine everything well.

Cover the slow cooker and set it on low for 6 to 8 hours, or high for 3 to 4 hours.

Once the cooking time is up, stir in the juice from half a lemon to brighten the flavors.

Ladle the warm, creamy chicken tikka masala into bowls and garnish with freshly chopped cilantro.