Peel the prawns and place the shell and heads into a large saucepan with the water. Bring to the boil and boil for 15 minutes to make prawn stock. Turn the heat to very low and keep warm. Put aside one large king prawn per person. Cut the rest of the prawns into large pieces and set aside.

Add the finely chopped shallots and garlic into a large pan along with two knobs of butter and cook over a low heat for 5 – 6 minutes until the shallots are soft and translucent.

Add the rice and stir well so that all the rice is coated in butter. Continue cooking for another two minutes stirring constantly.

Add the wine and increase the heat slightly and continue to stir. When the wine is absorbed add a ladle of warm prawn stock. When this is absorbed, add another and so on until almost all but a few spoons of the stock has been used. Add lemon zest and heat these through as the last of the stock is added. Check for seasoning and add salt and pepper as required. The mixture should now be soft and creamy and the rice al dente (still a little bite to the centre). 

Just as the risotto is almost cooked, melt the final knob of butter in a pan and put the whole king prawns and prawn pieces in and bring up to heat and then remove the prawns. Stir the cut prawn pieces through the risotto. 

Just before serving stir through the butter from heating the prawn. Spoon into a bowl and top with a whole king prawn each. Scatter with sprigs of dill.