"This mild, delicately fragrant curry has a rich creamy sauce that sure to be a winner. Serve with plain boiled rice or warm naan bread. This chicken korma tastes even better reheated on the next day."
Combine onions, chile pepper, garlic, and ginger in a blender; blend until smooth. Cut each chicken thigh into 4 pieces.
Heat oil in a large skillet over high heat and brown chicken pieces in batches until evenly browned on all sides, about 5 minutes per batch. Transfer to a slow cooker.
Melt butter in the same skillet over medium heat and add onion mixture once butter has melted. Cook until flavors are well combined, about 3 minutes. Stir in cumin, fennel, cardamom, paprika, turmeric, and cinnamon and cook for 1 minute more. Mix in chicken stock, sugar, and salt; bring to a boil. Pour contents of skillet over chicken in the slow cooker. Cover.
Cook on Low until chicken is cooked through and flavors are well combined, about 7 hours. Stir in heavy cream and ground almonds.