Bring a large pot of water to a boil. Add the spinach and blanch for 1-2 minutes until wilted.Drain the spinach and put it in a bowl of ice-cold water. This helps the spinach leaves retain their green color.This step makes it easier to work with the spinach since there's so much volume/bulk before it cooks down. Then finely chop the blanched spinach. You can also leave it as it is or even run it in a blender to get a smooth texture.
Heat oil in a pan/Kadai, add cumin seeds, let the cumin sizzle.
Then add onions, minced ginger, and garlic, green chili, and fry until onions turn light brown.
Next add diced tomato, turmeric powder, garam masala powder, salt, and cook for 1-2 minutes till the tomatoes are mushy.
Add the blanched spinach and stir in the full-fat coconut milk or heavy cream on a medium flame for 3-4 minutes. The sauce will thicken up as it cooks.
Squeeze some fresh lime juice and serve Indian creamed spinach curry hot with naan, rice, and onion slices.