Crack the crab claws and remove all of the meat, picking over it carefully - you'll need about 300 g/11 oz in total. Place in a bowl, cover with cling film and chill until needed. Reserve the crab shells.
Pour the brandy into the pan and allow to cook off for a minute or so. Add the reserved crab shells, diced carrots, onions, garlic and tomato purée and sauté for 1-2 minutes. Pour in 1 litre of water and bring to the boil, then reduce the heat and simmer for 30 minutes until well flavoured and slightly reduced.
Remove the pan from the heat and strain the mixture through a fine sieve into a clean pan, then simmer until reduced by half.
Pour in the cream and simmer for another 5 minutes.
Season to taste and keep warm or leave to cool and reheat as required.
Heat a sauté pan.
Add the remaining olive oil and then tip in the shallots.
Sauté for a minute or two and then stir in the reserved white crab meat and the coriander.
Continue to sauté for a minute or so until heated through, then season to taste and add a squeeze of lemon juice.
To serve, remove the soup from the heat and whisk in the butter until just combined.
Place a 5 cm/2 in cooking ring that is 5 cm/2 in deep in the centre of each warmed serving bowl and fill with the crab mixture.
Carefully remove the ring and garnish each one with a crab claw, then ladle the soup around it.
Finish with the coriander sprigs and serve with some of the bread rolls on the side.