Heat the browned butter in a deep frying pan and add the onions, ginger, and garlic and cook slowly until the onions are very soft, about 15 minutes.
Add the tomato paste, homemade curry powder, yellow curry powder, cinnamon stick, and chiles and give it a good stir; season with salt and pepper.
Add in the coconut milk and chicken stock and bring it back to a simmer; cook until the sauce has just begun to thicken, about 15-20 minutes.
Add the tomatoes, chicken, cilantro, and lemon juice; continue to simmer until the chicken is cooked through, and the sauce has finished thickening to desired consistency.
S&P to taste.
Add the fenugreek leaves and simmer for a minute or two more.
Garnish with cilantro.