11. FOR THE CRUST: Process 3/4 cup flour, salt and sugar in food processor until combined, about two 1-second pulses. Add butter and shortening, and process until dough just starts to collect in uneven clumps, about 10 seconds; dough will resemble cottage cheese curds with some very small pieces of butter remaining, but there should be no uncoated flour. Scrape bowl with rubber spatula and redistribute dough evenly around processor blade. Add remaining 1/2 cup flour and pulse until mixture is evenly distributed around bowl and mass of dough has been broken up, 4 to 6 quick pulses. Empty mixture into medium bowl.
2Sprinkle coconut rum and water over mixture. With rubber spatula, use folding motion to mix, pressing down on dough until dough is slightly tacky and sticks together. Flatten dough into 4-inch disk. Wrap in plastic and refrigerate at least 45 minutes or up to 2 days.
3Adjust oven rack to lowest position, place rimmed baking sheet on rack, and heat oven to 400 degrees. Remove dough from refrigerator and roll out on generously floured (up to 1/4 cup) work surface to 12-inch circle about 1/8 inch thick. Roll dough loosely around rolling pin and unroll into pie plate, leaving at least 1-inch overhang on each side. Working around circumference, ease dough into plate by gently lifting edge of dough with one hand while pressing into plate bottom with other hand. Refrigerate 15 minutes
4Trim overhang to 1/2 inch beyond lip of pie plate. Fold overhang under itself; folded edge should be flush with edge of pie plate. Using thumb and forefinger, flute edge of dough. Refrigerate dough-lined plate until firm, about 15 minutes.
5Remove pie pan from refrigerator, line crust with foil, and fill with pie weights. Bake on rimmed baking sheet 15 minutes. Remove foil and weights, rotate plate, and bake 5 to 10 additional minutes until crust is golden brown and crisp. Remove pie plate and baking sheet from oven
6FOR THE FILLING: While pie shell is baking, whisk cream, milk, eggs, yolks and vanilla together in medium bowl. Combine pumpkin puree, yams, sugar, maple syrup, ginger, cinnamon, nutmeg chocolate and salt in large heavy-bottomed saucepan; bring to simmer over medium heat, 5 to 7 minutes. Continue to simmer pumpkin mixture, stirring constantly and mashing yams against sides of pot, until thick and shiny, 10 to 15 minutes.
7Remove pan from heat and whisk in cream mixture until fully incorporated. Re whisk mixture and transfer to warm prebaked pie shell. Return pie plate with baking sheet to oven and bake pie for 10 minutes. Reduce heat to 300 degrees and continue baking until edges of pie are set 20 to 35 minutes longer. Transfer pie to wire rack and cool to room temperature, 2 to 3 hours. Cut into wedges and serve.