Bring water to a boil and blanch the spinach for 2-3 minutes. Drain and transfer to cold water to retain the bright green color.
Blend the spinach into a smooth puree and set aside.
Heat oil or ghee in a pan over medium heat. Add cumin seeds and let them splutter.
Add chopped onions and sauté until golden.
Stir in ginger garlic paste and cook for 1 minute.
Add chopped tomatoes and cook until soft.
Mix in turmeric, red chili powder, and salt.
Pour in the spinach puree and simmer for 4-5 minutes.
Add paneer cubes and cook another 3-4 minutes.
Sprinkle garam masala and drizzle heavy cream if using. Stir gently.
Serve hot with naan, roti, or rice.