Preheat the oven to 350 degrees and bake the piecrust (lined with foil and pie weights or dried beans) for 8 to 10 minutes, or until light golden brown. Remove the crust from the oven and cool. Increase the oven temperature to 375 degrees.
Boil the crawfish in plain water, then peel them, saving as much of the fat as possible.
Melt the butter in a large skillet and slowly (over medium heat) cook the leeks, celery, bell peppers, Essence and salt. Stir and cook about four minutes, until vegetables begin to soften. Sprinkle in the flour slowly and cook for 2 to 3 minutes to remove the raw flour taste. Remove from the heat and stir in the crawfish and fat. Add the garlic, return to the heat, and cook for 2 minutes. Add the hot sauce, Worcestershire and shallots and cook 2 minutes more, and then stir in the cream. Remove from the heat and add the egg a little bit at a time (Careful! If the pan's still too hot you'll end up with scrambled eggs), then stir in the breadcrumbs.
Pour the filling into the pre-baked piecrust and brush the edge of the dough with a little melted butter. Bake the pie at 375 degrees for 20-25 minutes, or until the crust is lightly browned.
Makes one pie