Bake a 9 inch pie crust using your favorite homemade recipe or refrigerated or frozen dough.
In a large saucepan (I use a 3 quart All-Clad metal), whisk sugar, cocoa powder, flour, salt, egg yolks, evaporated milk and water together. Put the saucepan over medium heat and stir for about five minutes or until mixture thickens and big bubbles start to form on the surface. From the time the mixture starts bubbling and boiling, continue stirring for an additional 1 1/2 to 2 minutes.
Remove from heat and pour into a glass bowl. Quickly whisk in the butter, then whisk in the vanilla. Put a piece of buttered parchment or wax paper over the top and let cool at room temperature for about an hour. Note: At this point you may think the filling seems to thin, but it will set when you chill it. Pour the slightly cooled filling into the baked pie shell and chill for several hours or until very cold.
When the pie is chilled, beat the cream until peaks start to form, beat in the sugar and vanilla until peaks are stiff, then put cream in a pastry bag or heavy duty zipper bag with the end snipped off and pipe it over the top. Sprinkle the toasted and chopped nuts, then drizzle with caramel syrup and chocolate syrup.