Place the prawns in a bowl and add the paprika, salt, chilli flakes, black pepper, and lemon juice. Mix well and set aside to marinate.
In a karahi, warm a little oil and add the chopped garlic. Cook gently until lightly golden.
Add the chopped green chillies and let them sizzle with the garlic for 3 minutes.
Add the chopped tomatoes, raise the heat to medium-high, and cook for 10-12 minutes, stirring often, until the water evaporates and a thick sauce forms.
Add the paprika, chaat masala, and coriander powder. Cook the masala for 6-7 minutes, allowing the spices to deepen in flavour.
Add the marinated prawns, lower the heat, and stir gently to avoid breaking them. Cook for 5-6 minutes only, until the prawns turn just opaque.
Turn off the heat and fold in the cream. Return to a low flame for 2 minutes to gently warm through.
Garnish with chopped parsley and serve hot with naan.
