Mughlai Sauce

Heat 2 tbsp oil in a pan on medium heat.
Add the ginger-garlic paste, green chilies (if using), and onions. Cook for 2–3 minutes until the onions soften. They should become translucent but not browned — this keeps the sauce lighter in flavor and color.
Add the cashews and cook for another 2–3 minutes, stirring frequently. Lightly toasting them enhances their nutty flavor and ensures a smoother puree.
Add the tomatoes and about 3/4 teaspoon of salt. Mix well.
Add the powdered spices including Red Chili powder, Coriander powder, Cumin powder and Turmeric. Do not add the garam masala yet.
Cook, stirring occasionally, for 8–10 minutes until the tomatoes completely soften and break down into a thick mixture. If the pan begins to dry out, add a splash of hot water.
Turn off the heat and let the mixture cool slightly. Transfer to a blender and puree until completely smooth.
In a clean pan, heat the remaining 1 tablespoon of oil (or use a combination of oil and butter for extra richness).
Strain the blended puree into the pan. Straining ensures a restaurant-style smooth texture and removes any coarse bits of onion or cashew.
Simmer for 2–3 minutes.
Add the heavy cream and mix well.
Crush the dried fenugreek leaves (kasuri methi) between your palms and sprinkle them in. Add the garam masala and stir.
Taste and adjust the seasoning by adding salt if needed and a pinch of sugar if the tomatoes are too tangy.