In a large bowl, combine the cubed chicken with yogurt, salt, and a pinch of ground spices. Let it marinate for at least 30 minutes, or up to overnight in the refrigerator for maximum flavor.
In a blender, add the cinnamon stick, green cardamom pods, cloves, fresh ginger, garlic cloves, and jalapeno. Blend until it forms a smooth paste. You may need to add a splash of water to help it blend.
In a large skillet, heat the sunflower oil over medium-high heat. Add the marinated chicken and cook until it is browned and cooked through, about 5-7 minutes. Remove the chicken from the skillet and set aside.
In the same skillet, add the butter. Once melted, add the spice paste and sauté for 2-3 minutes until fragrant. Then, add the crushed tomatoes, sugar, and salt. Let the mixture simmer for about 10 minutes, stirring occasionally.
While the sauce is simmering, blend the roasted cashews with a little water until smooth. Stir this into the sauce to add creaminess.
Return the cooked chicken to the skillet, and add the heavy whipping cream and crushed fenugreek leaves. Stir everything together and let it simmer for another 5 minutes until the flavors meld beautifully.
Serve the Famous Butter Chicken Recipe (Murgh Makhani) hot, garnished with fresh cilantro, alongside warm naan or steamed basmati rice. Enjoy the creamy, spiced goodness!