Blanch fresh spinach in boiling water 30–45 seconds, then plunge into cold water. Squeeze very hard until almost no liquid comes out. Chop finely (or pulse briefly; do not puree watery). If using frozen spinach, thaw and squeeze the same way.
Heat butter or oil in a skillet over medium heat. Add cumin seeds and let them crackle.
Add ginger-garlic paste and green chili. Cook 30–40 seconds until the raw smell fades.
Add spinach and salt. Cook 4–6 minutes, stirring, until the mixture looks thick and dry. Drag a spoon across the pan: you should see a clean line for a second.
Stir in crumbled paneer, cream cheese, garam masala, hing, kasuri methi, pepper, and optional cream. Cook 2 minutes more until the cream cheese melts into the filling. Taste and adjust salt.
Spread on a plate and cool completely before filling. Warm filling will open the seals.