Heat oil in a large pan over medium heat. Saute onions until lightly browned. Stir in garlic and ginger, and continue cooking for 1 minute more. Turn heat to low, add serrano peppers, and cook for an additional minute. Sprinkle in the chili powder, cumin, coriander, garam masala, and turmeric; cook until fragrant, about 1 minute.
Pour in tomato puree and ketchup; thin with water to desired consistency. Stir in the paneer and peas; cook to soften peas, 2 to 3 minutes. Stir in cream, and increase heat to medium-high. Allow the curry to come to a rolling boil, and cook for 3 to 4 minutes.