Butter a 2 quart baking dish or four 8 oz. gratin dishes.
In a medium size saucepan, melt 2 tablespoons
of the butter over medium heat. Add the flour
cook, stirring constantly for 2 minutes. Whisk
in the half and half. Bring the mixture to a
boil over medium high heat and cook, stirring
constantly, for 1 minute, or until thickened
slightly. Stir in the salt, white pepper, cayenne,
and lemon juice. Gently fold in the crabmeat.
Transfer the mixture to the prepared dish.
In a small skillet,
melt the remaining 2 tablespoons butter over
medium heat. Add the bread crumbs and cook,
stirring frequently, for 3 - 4 minutes, or until
light golden. Remove the pan form the heat and
stir in the Parmesan and parsley. Sprinkle the
crumbs evenly over the gratin dish.
Preheat the broiler.
Broil the gratin about 8 inches from the heat
for 2 - 3 minutes, or until the top is golden
brown and the crab mixture is hot and bubbly.