Chef John's Chicken Tikka Masala

Name: Chef John's Chicken Tikka Masala
Prep time: 25 min
Cook time: 45 min
Total time: 1 h 10 min
Cuisine: British
Ingredients: 1.5 pounds skinless, boneless chicken thighs; 1 tablespoon vegetable oil; 2 teaspoons kosher salt; 2 teaspoons garam masala; 2 teaspoons ground cumin; 1 teaspoon ground coriander; 1 teaspoon smoked paprika; 1 teaspoon ground turmeric; 0.5 teaspoon ground black pepper; 0.25 teaspoon cayenne pepper; 0.125 teaspoon ground cardamom; 2 tablespoons clarified butter (ghee), or more as needed; 1 onion, chopped; 0.25 cup tomato paste; 4 cloves garlic, finely grated; 1 tablespoon finely grated ginger, or more to taste; 1 cup crushed tomatoes; 1 (13 ounce) can coconut milk; 0.5 cup chicken broth, or as needed; 2 tablespoons chopped fresh cilantro; 0.5 teaspoon red pepper flakes; salt and ground black pepper to taste