Heat a large nonstick pan over medium-high heat. When hot, add the oil along with the ginger, garlic, and jalapeño. Cook until fragrant, about 1 minute. Add the garam masala, nigella, coriander, cumin, cardamom, cloves, and cinnamon. Cook, stirring constantly until fragrant, about 1 minute more. Add the mango, vinegar, sweetener, Dijon, and glucomann. Bring to a boil and then reduce the heat to a simmer and cook until thickened, about 10 minutes. Whisk in butter until smooth then transfer to a bowl and set aside. Wipe the pan clean.

Add another teaspoon of oil to the pan. Generously salt the chicken. When the oil is hot, add the chicken to the pan. Cook until browned, about 5-7 minutes. Flip and cook the second side until browned, another 5-7 minutes. When the chicken is cooked through, add back the mango sauce and toss to combine. Serve with fresh cilantro, if desired.