Step 1: Add the Chicken to the Slow Cooker - Start by adding the cubed chicken breast right into the bottom of your slow cooker. I like to cut the chicken into bite sized pieces so every spoonful gets a good mix of tender chicken and sauce. Try to keep the pieces roughly the same size, because that helps them cook evenly. No need to brown the chicken first for this easy version. The slow cooker will handle it, and the sauce will give it plenty of flavor as it cooks.
Step 2: Whisk the Tomato Yogurt Sauce - In a medium mixing bowl, whisk together the tomato puree, plain yogurt, salt, pepper, garam masala, turmeric, cumin, granulated sugar, ginger, and garlic. Take a minute here to really mix it well. The yogurt should blend into the tomato puree, and the spices should be evenly spread through the sauce. This is where all that wonderful flavor starts coming together. It may not look fancy yet, but trust me, once it cooks down around the chicken, it turns into something rich and comforting.
Step 3: Pour the Sauce Over the Chicken - Pour the sauce over the chicken in the slow cooker, making sure you scrape the bowl so none of those spices get left behind. That sauce is the heart of the recipe, and you want every bit of it in there. Use a spoon or spatula to move the chicken around a little so the sauce can settle between the pieces. I always tell my kids this is the part where dinner starts looking like dinner.
Step 4: Add the Onion and Stir Everything Together - Add the diced yellow onion to the slow cooker, then gently stir everything so the chicken is coated and the onion is mixed through the sauce. The onion will soften as it cooks and add a little natural sweetness. Do not worry if the sauce looks a bit thick at this stage. As the chicken cooks, it releases juices, and everything loosens up into a lovely simmering sauce.
Step 5: Cook Until the Chicken Is Tender - Cover the slow cooker and cook on high for 3 to 4 hours or on low for 6 to 8 hours. The low setting is my favorite when I have the time, because the chicken gets especially tender and the spices have more time to settle in. The high setting works beautifully too when the day gets away from you. The chicken should be fully cooked and tender enough to cut easily with a spoon.
Step 6: Stir in the Cream and Finish - When the cooking time is done, stir in the heavy cream. This is the little finishing touch that makes the sauce smooth, rich, and restaurant cozy. Give everything a gentle stir and let it sit for a few minutes so the cream warms through. Taste the sauce and add a tiny pinch more salt if you think it needs it. Top with fresh cilantro right before serving, and get the rice and naan ready because that sauce deserves a proper landing place.