In a skillet pan, over medium heat, cook the diced onion with the oil until softened and light golden (about 5-7 minutes).
1 tablespoon olive oil, 1 yellow onion
Stir in the garlic and ginger, and cook for an additional 1 minute until very fragrant.
4 cloves garlic, 1 tablespoon grated fresh ginger or ginger paste
Transfer the onion mixture into a slow cooker.*I use a 5.5 QT slow cooker, but anything from 5-7 QT will work fine Add the crushed tomatoes, heavy cream, tomato paste, garam masala, cumin, coriander, turmeric, smoked paprika, and salt to the slow cooker. Stir to combine.
1 can (28 oz) crushed tomatoes, 1 cup heavy cream, 2 tablespoons tomato paste, 2 tablespoons garam masala, 1 tablespoon ground cumin, 1 teaspoon ground coriander, 1 teaspoon turmeric, 1 teaspoon smoked paprika, 1 teaspoon kosher salt
Add the chicken pieces to the slow cooker and stir to coat them evenly in the tikka masala sauce.
2 pounds boneless, skinless chicken breasts or thighs
Cover the slow cooker with the lid and cook on LOW heat for 6-7 hours, or until the chicken is tender and cooked through (165 degrees F).
Taste the sauce and adjust the seasonings if needed.*The long cook time can sometimes mute the flavors, so I will usually add just a pinch of kosher salt at the end. Serve over cooked white rice with naan bread on the side.