Prepare the Chicken: Remove the giblets from the whole chickens and set aside. Cut off the chicken wings and set aside with the giblets. Peel the skin off the chicken and cut the chicken into 2 skinless breasts and 2 skinless legs with thighs. Put the chicken back meat with wings and giblets aside.

Make Chicken Broth: In a large stockpot, pour 4 cups of water over medium-high heat. Add the giblets, wings, and chicken back meat. Bring to a boil, then reduce to medium-low, cover, and heat for 30-40 minutes. Discard the parts and save the strained broth.

Sauté Aromatics: Clean and wipe the bottom of the stockpot. Add vegetable oil over medium-high heat. Add chopped red onions, garlic, ginger, cumin seeds, cinnamon stick, cardamom seeds, cloves, and bay leaves. Cook for about 5-8 minutes, stirring occasionally until onions become golden translucent. If the mixture sticks badly to the bottom of the pot, either reduce heat to medium or add a tablespoon of the broth.

Sear and Simmer Chicken: Add chicken legs with thighs and breast to the onion mixture. Mix so the mixture is coated on all sides of the chicken. Cover, reduce to medium-low, and let simmer for 10 minutes. Uncover, add plain yogurt, garam masala, curry powder, coriander powder, turmeric powder, cayenne pepper (adjust to desired heat level), and salt. Mix well together so everything is blended and chicken is coated. Cover and heat on medium for 15 minutes.

Add Tomatoes and Broth: Now add diced tomatoes and 2-3 cups of broth (according to taste for gravy consistency). Cover and cook on medium-high, covering the pot halfway, for 30-40 minutes.

Final Simmer and Garnish: Uncover pot and give a gentle stir as chicken is getting tender. Be careful, a rough stir may shred chicken. Check if the chicken is cooked thoroughly and tender. Taste the gravy to see if it needs any more salt or pepper. Add chopped cilantro and gently stir. Cover and cook on medium-low for 10-15 minutes. Turn off the heat and add hard-boiled eggs (each cut into two pieces) immersed in the gravy to absorb flavor. Let stand for 5 minutes or more.

Serve: Serve with Indian Basmati Rice, Chapati, or Paratha (Indian flat round wheat Bread) with a side of sliced onions and diced cucumbers mixed with plain yogurt (blended with water, a pinch of salt, and mint powder) sauce.