Melt butter on a tawa or frying pan or skillet.
Add the carom seeds and fry them for a few seconds or till aromatic.
Add the onions and saute stirring often till they soften and turn translucent.
Add the ginger-garlic paste, green chilies, finely chopped capsicum/green bell pepper and saute for about 3 minutes on a low to medium-low heat.
Then add the red chili powder, turmeric powder, coriander powder and pav bhaji masala. If you don't have pav bhaji masala, then swap it with garam masala powder + dry mango powder.
Stir and saute for about a minute.
Then add the tomato puree and salt as needed.
Stir well and saute till you see butter releasing from the sides and the masala has thickened a bit. This takes about 8 to 10 minutes on a low heat.
If the tomato masala looks dry, then add 1 or 2 tablespoons of water and continue to saute.
Add the paneer cubes and mix gently so that the masala coats the paneer cubes evenly. Switch off the heat.
Then add the crushed dry fenugreek leaves and mix gently.
Garnish with coriander leaves and serve paneer tawa masala with roti, naan, paratha or bread. Accompany with a few wedges of lemon slices which can be drizzled on the tawa paneer and a side onion salad.