Crust:

For Crust: Preheat oven to 350 degrees F. Place graham cracker crumbs in medium bowl. In food processor fitted with steel blade, combine walnut pieces and sugar. Process only until walnuts are finely ground (you don't want walnut paste here). Turn ground walnut mixture into bowl with graham cracker crumbs; stir thoroughly with large spoon to mix well. Stir in melted butter until well-combined.

Turn mixture into 10 inch heatproof glass pie plate. Use about two-thirds of crust mixture to form sides of crust, making sure to form a high rim that stands slightly above the edge of the pie plate. Compact remaining crust mixture evenly on bottom of pie plate; try not to get crust too thick where bottom and sides meet. Bake in preheated oven for 8 to 11 minutes, or until rim is a slightly darker gold than rest of crust. Remove to cooling rack; cool completely before filling.

For Filling: In two quart, heavy-bottomed pot, combine sugar, cornstarch, and salt. Whisk to mix thoroughly; set aside. In small bowl, combine egg yolks with about 1/4 cup milk (reserve remainder); with fork, beat to blend well. Set aside, along with remaining milk. Place chopped bittersweet chocolate in small heatproof bowl near stovetop. Place butter in medium heatproof bowl near stovetop. Have nearby the rum, a fine strainer, and a two cup capacity, heatproof liquid measuring cup.

Heat remaining milk in small saucepan over low heat, stirring occasionally, until warm. Add about 1/4 cup of warmed milk to sugar-cornstarch mixture; with whisk, stir to combine (do not beat). Stir in yolk mixture, then gradually stir in rest of warmed milk. Place over medium heat; stir constantly until mixture comes to a boil. If using a whisk to stir, make sure you get into "corners" of pot while stirring. If there are any undissolved lumps of cornstarch, press them out with a spatula or the back of a spoon. Just before it boils, the mixture will become very lumpy and look awful. Continue stirring gently; it should smooth out as it boils. Boil and stir one minute. Remove from heat.

Immediately place strainer over the two cup liquid measure. Strain in enough custard to measure 1-1/2 cups. Turn the measured custard into the small heatproof bowl with the chopped chocolate, and let stand for a couple of minutes to melt the chocolate. Meanwhile, strain remaining custard into medium heatproof bowl (the bowl containing the butter). Add rum to medium bowl. Using a rubber spatula, gently fold butter and rum into custard only until incorporated (do not beat or handle more than necessary). Pierce a piece of plastic wrap large enough to cover the medium bowl in about a dozen places with the tip of a sharp knife or a toothpick; place pierced plastic wrap directly onto surface of butter-rum custard. Place this custard in refrigerator. Using a clean rubber spatula, fold melted chocolate into custard in small bowl, again handling gently and as little as possible. Repeat plastic wrap procedure with small bowl, but do not chill chocolate custard. Let stand 30 minutes at room temperature. During this time, tear off a piece of plastic wrap large enough to cover surface of pie. Pierce as above in about twenty places. Set aside.

Just before the 30 minutes are up, peel the banana and slice thinly into 1/8 inch rounds. Turn the chocolate custard (which will still be warm) into the cooled pie crust, and spread it evenly over the bottom. Working quickly, place banana slices all over the chocolate custard (I make concentric circles, but you can place them randomly if you wish). Remove rum custard from refrigerator (it will still be warm, too). Pour rum custard slowly over banana slices, then spread evenly if necessary. The pie plate will be quite full. Place the pierced plastic wrap directly onto the surface of the rum custard, then chill the pie at least 4 hours before serving.

About 20 minutes before serving, place a medium bowl and beater(s) in the refrigerator or freezer to chill. Have ready the grated or shaved chocolate and the banana(s) for serving. Assemble plates, napkins, and forks.

In chilled medium bowl with chilled beater(s), beat cream at high speed just to soft peaks. Add confectioners' sugar and rum. Beat at low speed until incorporated, then return to high speed. Beat cream to stiff peaks.

Quickly peel and thinly slice bananas. Cut slices of the pie; place each slice on a plate. Place several banana slices, overlapping, on top of each slice. Place a large spoonful of the whipped cream along one side of each slice, then lightly sprinkle all with the chocolate. Serve immediately!

10 to 12 servings