In a medium Dutch oven, set over medium heat, add the butter. When the butter has melted, add the cinnamon stick, cardamom pods and whole clove. Add the onion, garlic, jalapeño, ginger and spices: garam masala and turmeric. Mix until the everything is completely coated. Cook until softened about 4 to 6 minutes. Remove the cinnamon stick, cardamom pods and whole clove.
To the blender, add cooked onion mixture and can of diced tomatoes. Blend until smooth. Give it a taste and adjust the salt to your liking. I added a few pinches.
To the same Dutch oven, no need to wash it out, add a few teaspoons of oil. When warm, add the mushrooms. Cook until softened, about 5 to 6 minutes. Pour the sauce back into the pot and mix. Bring up to a simmer and cook for 2 to 3 minutes.
Serve with a side of naan and basmati rice.