Season the chicken pieces evenly with 1 teaspoon of salt. Heat the olive oil in a large skillet over medium heat. Add the diced yellow onion and cook, stirring occasionally, until softened and translucent, about 5-7 minutes. Add the minced garlic and grated fresh ginger, and cook for another 1-2 minutes until fragrant.

Stir in the garam masala, ground cumin, ground coriander, and ground turmeric. Cook for 1 minute, stirring constantly, until the spices are aromatic. Add the tomato paste and cook for an additional minute, stirring it into the spices and aromatics.

Transfer the aromatic mixture from the skillet to your 6-quart slow cooker. Add the seasoned chicken pieces and the can of crushed tomatoes. Stir everything together gently to ensure the chicken is coated in the sauce.

Cover the slow cooker and cook on high for 3-4 hours, or on low for 6-8 hours, until the chicken is incredibly tender and easily shreds with a fork. The sauce should have thickened slightly and the flavors melded beautifully.

Once cooked, carefully remove the chicken pieces from the slow cooker and shred them using two forks, or cut them into bite-sized chunks if you prefer. Return the chicken to the slow cooker. Stir in the heavy cream until fully incorporated into the sauce.

Taste the tikka masala and add more salt if needed. Serve hot, garnished generously with fresh chopped cilantro. It's fantastic with fluffy basmati rice and warm naan bread for dipping!