Combine cumin, coriander, cayenne, and salt in a small bowl for the chicken spice mix.

Sprinkle spice mixture on both sides of chicken and press into the meat.

Set aside the spiced chicken in a glass dish.

In a large bowl, combine yogurt, vegetable oil, minced garlic, and grated ginger for the marinade.

Spoon yogurt mixture evenly on both sides of the chicken, ensuring full coverage.

Place marinated chicken breasts in a glass dish, cover with plastic wrap, and refrigerate for at least 1 hour.

Preheat oven to 400°F (200°C).

Place chicken breasts on a rimmed baking sheet in a single layer.

Bake for 40 minutes, turning halfway through after 20 minutes.

Ensure chicken is fully cooked and lightly browned.

Remove from oven and let the chicken rest for 10 minutes.

Slice the chicken into bite-sized pieces.

While the chicken is baking, prepare the sauce.

Heat vegetable oil in a large Dutch oven over medium heat.

Add diced onion and cook, stirring frequently, until light golden brown (approximately 10 minutes).

Add minced garlic, grated ginger, minced serrano chili, tomato paste, and garam masala.

Cook, stirring continuously, until fragrant (about 3 minutes).

Add crushed tomatoes, sugar, and salt.

Bring mixture to a boil, then reduce heat to medium-low.

Cover and simmer for 15 minutes, stirring occasionally.

Stir in heavy cream and return to a simmer.

Remove the pan from the heat and cover to keep warm.

Toss the sliced chicken in the warm masala sauce, ensuring not to cook further.

Stir in chopped fresh cilantro and check seasoning.

Garnish with additional cilantro, if desired.

Serve hot with rice and naan bread.