Preparing the Pecan Crust:
Preheat oven to 350 degrees F.
Finely grind pecans in a food processor. Add flour and salt. Mix well. Transfer to a large mixing bowl and cut in butter, working butter into flour with 2 knives until dough is in crumbs the size of small peas. Add ice water and evenly incorporate into the mixture, which should remain fairly crumbly. Roll out dough to a 1/8-inch thickness on a lightly floured surface. Press dough into a lightly greased 9-inch tart pan, starting with the sides and then the bottom. Bake crust for 20 minutes, or until golden.
Note: Dough can be made ahead of time. If doing so, wrap dough tightly in plastic wrap and refrigerate. Allow dough to come to room temperature before rolling out.
Preparing the Filling:
Preheat oven to 300 degrees F.
In a skillet, saute onion in butter until translucent. Add crabmeat and cook just until heated through, then remove from heat. Blend cream cheese until smooth in a mixer fitted with a paddle, or by hand using a wooden spoon. Add Creole cream cheese and mix well. Mix in eggs 1 at a time. Gently fold in the crabmeat mixture. Stir in hot sauce and season, to taste, with salt and white pepper. Spoon filling into prepared crust. Bake for 30 to 40 minutes, or until firm to the touch.
Preparing the Meuniere Sauce and Garnish:
Combine lemon, Worcestershire sauce and hot sauce in a heavy saucepot. Reduce over medium heat, stirring constantly with a wire whisk until mixture becomes thick and syrupy. Whisk in heavy whipping cream. Reduce heat to low and slowly blend in butter, 1 cube at a time, adding additional butter only after each cube has been completely incorporated into the sauce. This process is called "mounting the butter." Remove from heat and continue to stir. Season with salt and pepper, to taste. Strain through a fine strainer and keep warm.
Saute mushrooms in 2 tablespoons butter until tender and all moisture has cooked off. Excess water from the mushrooms may break your sauce if it isn't cooked off. Stir mushrooms into Meuniere sauce. Melt 1 tablespoon butter in a saute pan and warm crab fingers over low heat. Season with salt and pepper, to taste.
Slice cheesecake and top each piece with warm Meuniere sauce and 3 crab claws.