Heat the butter and olive oil in a large skillet over medium-high heat. Cook the onions until they become soft and translucent, about 3-5 minutes. Stir in the ginger and garlic and cook for an additional 1-2 minutes.
Add the chicken breast to the skillet with the cooked onions. Add the tomato paste, red curry paste and the Indian spices to the chicken. Season with salt and pepper. Stir in the chicken until it's well coated with the onions, tomato and curry pastes and spices.
Pour the coconut milk over the chicken mixture and stir to combine. Bring the mixture to a boil, and then set the heat to low, and simmer for 20 minutes.
Serve over white rice and/or naan, and garnish with cilantro, if desired
Storage: Store any leftovers in an airtight container. They will last about 3-4 days in the fridge.Make Ahead: If you want to prepare some of the dish ahead of time. You can saute the onions, garlic and ginger with the butter and olive oil. Then transfer the onion mixture to a bowl, add all the ingredients on top of it and stir to combine. You can do this up to one day in advance. When ready to cook, just put everything in a pan, bring to a boil, then simmer on low heat for 20 minutes. Sourcing: You can find most of the spices at major grocery stores. Garam masala may not be as widely available, but you can find at Indian specialty stores.Substitutes: For best results, follow the recipe as is. If you can't find garam masala, you can make your own blend. Here's are two popular substitutions: 1 part cumin plus 1/4 part allspice. Or any combination of: Coriander, Cumin, Black Peppercorns, Cardamom, Cloves, Nutmeg.Nutrition Label: Please note the nutrition label does not include the rice or naan.