Chicken Curry with Potatoes and Squash

Name: Chicken Curry with Potatoes and Squash
Ingredients: 2 tablespoons ground coriander; 1 tablespoon plus 1 teaspoon pure chile powder, such as pasilla; 1/4 teaspoon turmeric; 3 tablespoons water; 1/2 cup vegetable oil; 3 onions, halved and thinly sliced; 8 garlic cloves, thinly sliced; One 1-inch piece of fresh ginger, peeled and thinly sliced; 12 curry leaves; 2 teaspoons garam masala; 1 teaspoon freshly ground black pepper; One 3 1/2-pound chicken, cut into 8 pieces, wing tips removed; Kosher salt; 1 large baking potato, peeled and cut into 1-inch dice; 3/4 pound butternut squash, peeled, seeded and cut into 1/2-inch dice; One 14-ounce can unsweetened coconut milk; 1 cup chicken stock or low-sodium broth