Step 1: Pat the chicken cubes dry with paper towels and season them generously with 1/2 tsp salt and 1/4 tsp black pepper.
Step 2: Heat 1 tbsp unsalted butter and 1 tbsp olive oil in a large, oven-safe skillet (preferably cast iron) over medium-high heat. Once hot, add half of the seasoned chicken (do not overcrowd) and sear for 3-4 minutes per side, until golden brown. Remove chicken to a plate and repeat with the remaining chicken. Set all seared chicken aside.
Step 3: Add the remaining 1 tbsp unsalted butter to the same skillet. Add the finely chopped yellow onion and cook over medium heat for 5-7 minutes, stirring occasionally, until softened and translucent.
Step 4: Stir in the minced garlic and grated fresh ginger. Cook for another 1 minute until fragrant, being careful not to burn the garlic.
Step 5: Add the ground cumin, ground coriander, turmeric, chili powder, and garam masala to the skillet. Cook, stirring constantly, for 30 seconds to 'bloom' the spices, releasing their full aroma.
Step 6: Pour in the crushed tomatoes and chicken broth. Bring the mixture to a gentle simmer, scraping any browned bits from the bottom of the pan with a wooden spoon.
Step 7: Return the seared chicken pieces to the skillet, nestling them into the sauce. Reduce the heat to low, cover the skillet, and simmer for 10-15 minutes, or until the chicken is cooked through and tender.
Step 8: Stir in the heavy cream and cook for an additional 2-3 minutes, uncovered, until the sauce is heated through and slightly thickened. Taste and adjust seasoning with remaining salt and pepper, or more chili powder if you prefer more heat.
Step 9: Garnish generously with fresh cilantro and serve hot. This dish is excellent served with basmati rice or warm naan bread.