Step 1: Season the Chicken - Add the bite sized chicken thigh pieces to the bottom of your slow cooker. Sprinkle the salt, pepper, and garlic powder over the chicken, then give it a gentle toss so every piece gets a little seasoning. I like chicken thighs here because they stay juicy in the slow cooker, even after several hours. Chicken breasts can work too, but thighs are more forgiving, and that matters when life gets busy.
Step 2: Add the Aromatics - Scatter the finely diced onion over the chicken, then add the minced garlic and ground ginger. This is where the sauce starts building real flavor. The onion softens down as everything cooks, the garlic gets mellow and savory, and the ginger brings that warm little lift that keeps the sauce from tasting flat.
Step 3: Sprinkle in the Spices - Add the garam masala, curry powder, cumin, paprika, turmeric, and cayenne if you are using it. Do not worry if it looks like a lot of spice sitting on top. Once the liquids go in and everything starts cooking, those spices bloom into the sauce and make the whole kitchen smell incredible. If you are cooking for kids or anyone sensitive to heat, skip the cayenne and let people add spice at the table.
Step 4: Pour in the Tomato Ingredients - Pour in the tomato sauce, diced tomatoes, chicken broth, and tomato paste. The tomato sauce gives you that smooth base, the diced tomatoes add some body, and the tomato paste makes the sauce taste richer. I like to stir gently at this point, just enough to get the tomato paste moving through the liquid and coat the chicken with all that spiced tomato goodness.
Step 5: Add Brown Sugar and Stir - Add the brown sugar and stir everything together gently. That little spoonful might not seem like much, but it helps balance the tomatoes and spices. You are not making the sauce sweet. You are just softening the sharp edges so the final chicken tikka masala tastes round, cozy, and full.
Step 6: Slow Cook Until Tender - Cover the slow cooker and cook on low for 5 to 6 hours or on high for 3 to 4 hours. The chicken is ready when it is tender and cooked through, and the sauce has had time to pull all those spices together. I usually prefer low because it gives the chicken more time to relax into the sauce, but high works just fine when the day gets away from you.
Step 7: Stir in the Cream - Once the chicken is tender, stir in the heavy cream until the sauce looks smooth and creamy. This is the part where the whole dish changes from good to really good. Add the cream at the end so it stays silky and does not separate during the long cooking time.
Step 8: Warm and Finish - Cover the slow cooker again and let everything cook for another 10 to 15 minutes, just until heated through. Give it one final gentle stir, then sprinkle chopped cilantro over the top. Serve it warm over white rice with naan bread if you have it. Around my table, naan is not optional for long because everybody wants something to scoop up that extra sauce.