Mousselines of lobster with Champagne beurre blanc and caviar

If the lobsters are alive when you get them home, then kill them humanely by inserting a needle or sharp knife into the centre of the cross on their heads. Alternatively, you can ask a fishmonger to do this for you

Bring 2 litres of water to the boil in a saucepan with 30g of salt. Remove the eggs from the hen lobsters (if there are any) and reserve in the fridge. Rinse the lobsters in cold water, then plunge into the boiling water and cook for 12 minutes. Drain immediately and leave to cool

Remove the meat from the shells, trying to keep the tail meat in large pieces. Cut the tails into medallions and wrap in a damp cloth. Finely dice the remaining lobster meat and set aside

Rinse the large lobster in cold water and detach the claws and tail. Using a mallet, crack the claws and take out the meat (if you’re struggling to get the raw meat out of the shells, plunging the lobster into boiling water for 10-15 seconds can help loosen it). Cut open the tail shell with scissors and use a spoon to scrape out the meat. Immediately discard the gritty sac from near the coral in the head – you should get around 400g of raw lobster meat from the large lobster

Place the meat from the large lobster in a blender or food processor along with the egg whites and 2 teaspoons of salt. Blitz until thoroughly combined and smooth, then rub the mixture through a sieve into an earthenware or stainless steel bowl set in crushed ice

Work the mixture with a wooden spoon or spatula, stirring in the double cream a little at a time until it is all mixed in. The texture should be soft and slightly runny. Reserve the mixture in the fridge

To cook the spinach, blanch the leaves in boiling water for 30 seconds, then drain and plunge into iced water. Dry the leaves by spreading them out flat on a tea towel

Preheat an oven to 200°C/gas mark 6. Using a pastry brush, thickly coat the insides of your dariole moulds with melted butter, then line the bases and sides with the dried spinach leaves, ensuring there is plenty of overhang so you can seal the tops

Half-fill the moulds with the lobster mousse, then place a very small amount of caviar in the centre with the handle end of a teaspoon (you want to have plenty of caviar leftover to serve). Add a few lobster eggs (if using) and some of the reserved finely diced lobster meat. Top up with more lobster mousse, then fold the spinach leaves over to enclose the filling completely

Place the filled dariole moulds into a deep baking dish and heat a pan of water to 70°C. Pour the water – ensuring it is the correct temperature – into the baking dish so the water comes halfway up the sides of the moulds. Cover the baking dish with foil, then transfer to the oven and cook for 18 minutes

Meanwhile, prepare the sauce. Add the shallots and Champagne to a saucepan and simmer until reduced and slightly syrupy. Take the pan off the heat and beat in a little butter, then return to a low heat and beat in the remaining butter, a little at a time. When the butter becomes creamy and begins to foam, crush any remaining lobster eggs with the flat of a knife and stir them into the sauce, which will give it a delicate orange tinge. Season to taste and keep warm

Wrap the reserved lobster medallions in foil and, once the mousselines are cooked, place in the oven to warm through

To serve, very carefully unmould the lobster mousselines onto serving plates (they will be very fragile). Place the warmed lobster medallions alongside, and any remaining diced lobster meat on top of the mousselines. Finish with small quenelles of caviar, then pour the warm sauce around the plate (ideally through a conical sieve) and serve immediately