Fresh crabs should feel heavy for their size. You can buy a crab live and boil it yourself; alternatively, ask your fishmonger to kill it for you, or buy it ready-cooked. If buying cooked crabmeat ...
I have written recipes for seafood risotto before but never made ... add 2¼ litres/3¾ pints water and bring to the boil. Turn down the heat and simmer gently for 20 minutes.
then add the heavy cream and return to a boil. Add the scallops, shrimp, and lobster and cook about 4 to 5 minutes, until the seafood is done. Stir in the mascarpone and butter. Add the kale ...