Heat your saucepan on medium heat, add oil and butter together. Once hot, add the cinnamon, bay leaf, cloves, black cardamom, green cardamom, and cumin seeds.
Let the whole spices sizzle in the oil & butter mixture then add the chopped onions. While the onion is cooking, add the chopped ginger, garlic, and serrano chili. We are using the whole serrano chili if you want to cut back on the heat, then deseed your serrano or use just half of the serrano.
Saute for about a minute or two until the onion turns translucent, we are not going to let onions turn brown.
Now add turmeric, coriander powder, cumin powder, and red chili powder. Let all your spices saute for few seconds.
Add your chopped tomatoes along with cashews and season it with salt. Lightly saute everything and add water. Cover the saucepan and let it cook for 10 to 15 minutes until tomatoes are softened. Once it's done, turn off the heat and allow it cool down.
While the curry mixture is cooling down let's start working on Koftas. In a mixing bowl add boiled and mashed potatoes along with grated Paneer, finely chopped cilantro, ginger, serrano, cornflour, cashews, and salt to taste.
Now mix everything with your hands to form a dough and start forming Koftas. To form a Kofta take a spoon full of dough and roll between your palm to give it a shape. We decided to go with an oblong shape for our Koftas.
Now in another pan heat enough oil to deep fry your Koftas. Fry the Koftas until golden brown on medium-high heat. Remove your fried Koftas on a paper towel.
Now it's time to work on the curry. Discard the bay leaf from the mixture and transfer it to a blender to make a smooth paste.
Pass the blended mixture through a strainer to get the smooth and velvety texture.
Transfer the curry into the saucepan on medium heat and cook it for about a minute or two. Add powdered fenugreek leaves, sugar, and salt to taste.
Check the consistency of your curry, add water if necessary. Allow the curry to cook for 3 to 4 minutes and turn off the heat. Just before serving, add and mix the heavy cream to the curry, and it's ready to serve.