Combine spinach, butter, grated cheese, sifted flour, salt, pepper and mustard to taste. Grease a baking tin.
Line with greaseproof paper, butter and flour the paper. Pour in the spinach mixture. Bake at 200°C for 10 minutes. Invert and quickly peel off the paper, spread the filling on top, and raising the paper as a support, gently roll up.
For filling: Fry the chopped onions in 2 tbsp. Butter till golden brown. Add the tomatoes, skinned and chopped and fry till slightly dry.Add the chopped paneer, chopped capsicums, salt and pepper to taste