Step 1 Kill the lobsters by making a cut just behind the head. Remove the claws and tails. Put the tails and claws in a large bowl and cover with boiling water. Blanch the claws for 2 1/2 minutes and the tails for 3 minutes. Remove them from the boiling water and shock them in ice water until chilled. (These can be cooked ahead of time, then brought to room temperature when ready to use.)
Step 2 Remove the meat from the tails and cut on the bias into 3 or 4 medallions. Remove the meat from the claws and knuckle and set aside. Clean the body shells, removing the innards and scraping the gills. Reserve the shells to make stock for the cream sauce.