For the crust
2 1/2 cups all purpose flour
1 tablespoon sugar
3/4 teaspoon salt
10 tablespoons (1 1/4 sticks) chilled unsalted butter, cut into 1/2-inch pieces
1/3 cup chilled solid vegetable shortening, diced
6 tablespoons (or more) ice water
for the filling
3 large eggs
1 cups packed light brown sugar
1/2 cup light corn syrup
2 tablespoons rum
1/2 teaspoon vanilla
1/4 teaspoon salt
1/2 stick (1/4 cup) unsalted butter, melted and cooled slightly
1 1/2 cups dry-roasted macadamia nuts, toasted and coarsely chopped
1 cup sweetened flaked coconut
for the ganache to drizzle
9 ounces bittersweet chocolate, chopped
1 cup heavy cream
2 tablespoons unsalted butter
Blend flour, sugar and salt in processor. Add butter and shortening and cut in using on/off turns until mixture resembles coarse meal. Add 6 tablespoons ice water and process until moist clumps form, adding more water by teaspoonfuls if dough is dry. Gather into ball, then flatten into a disk. Wrap in plastic wrap and chill 2 hours.
Preheat the oven to 375F. Prepare a 10-inch tart pan with cooking spray.
Roll out dough into a 13-inch round on a lightly floured surface with a lightly floured rolling pin. Fit into tart pan and trim edges. Chill shell until firm, about 30 minutes. Lightly prick bottom of shell all over with a fork, then line with foil and fill with pie weights. Bake until side is set and edge is pale golden, about 20 minutes. Carefully remove foil and weights and bake shell until deep golden, 10 to 15 minutes more. Leave oven on.
Whisk together eggs, corn syrup, rum, brown sugar, vanilla, and salt until combined, then whisk in melted butter, nuts, and coconut. Pour filling into tart shell and bake until set in center, 25 to 30 minutes. Cool in pan on a rack 30 minutes, then remove side of pan and cool tart to room temperature, 1 1/2 to 2 hours more.
Once the pie is completely cooled, prepare the chocolate ganache to drizzle on the tart. To make the ganache, place the chocolate into a medium bowl. Heat the cream in a small sauce pan over medium heat. Bring just to a boil, watching very carefully because if it boils for a few seconds, it will boil out of the pot. When the cream has come to a boil, pour over the chopped chocolate, and whisk until smooth. Add in tablespoons of butter, one at a time. Drizzle over the tart to decorate.