Butter Chicken (Murgh Makhani)

In a large bowl, combine the chicken, yogurt, lemon juice, 1 tsp turmeric, 1 tsp garam masala, and half the ginger-garlic paste. Mix well, cover, and marinate in the fridge for at least 2 hours or overnight for best flavor.
Heat a large nonstick skillet over medium-high heat with 1 tbsp of the butter. Working in batches so you don't crowd the pan, sear the marinated chicken for 3-4 minutes per side until lightly browned but not fully cooked through (it will finish in the sauce). Set aside on a plate.
In a large heavy-bottomed pot, heat the oil and remaining 2 tbsp butter over medium heat. Add the chopped onion and cook, stirring often, for 6-7 minutes until soft and golden, not browned or burnt.
Add the remaining ginger-garlic paste and cook for 30 seconds, stirring constantly, until fragrant; do not let it burn or it will taste bitter.
Stir in the remaining 1 tsp turmeric and the chili powder, cooking for 15 seconds to bloom the spices in the fat.
Pour in the crushed tomatoes, add 1 tsp salt and the sugar, and bring to a simmer. Reduce heat to low, cover, and cook for 15 minutes, stirring occasionally, until the tomatoes darken and thicken slightly.
Remove the pot from heat and let cool for 5 minutes, then blend the sauce until completely smooth using an immersion blender or a stand blender (vent the lid to let steam escape).
Return the smooth sauce to the pot over medium-low heat. Add the seared chicken along with any juices, cover, and simmer for 10-12 minutes, stirring occasionally, until the chicken reaches an internal temperature of 165F.
Stir in the heavy cream and remaining 1 tsp garam masala. Simmer uncovered for 3-4 minutes until the sauce is glossy and slightly thickened.
Crush the dried fenugreek leaves between your palms and sprinkle into the pot; stir through. Taste and adjust salt.
Turn off the heat and let the curry rest for 5 minutes before serving; this allows the flavors to meld and the sauce to settle to the right consistency.
Serve hot, garnished with a small swirl of cream if desired, alongside naan or steamed basmati rice.