How to Make It
Preheat oven to 350°F. Line a 9 by 13-inch baking dish with two crisscrossed pieces of parchment paper, leaving an overhang on all sides. Coat the parchment with nonstick cooking spray.
Make the crust: In a large bowl, whisk together flour, sugar, and salt. Slowly add melted butter and stir with a fork and press gently with your hands until combined. Press into the bottom of prepared pan. Prick all over with a fork. Bake until puffed and lightly browned, 18 to 20 minutes, rotating halfway through.
Meanwhile, make the filling: In a large bowl, whisk together pumpkin puree, butter, brown sugar, flour, cinnamon, vanilla, ginger, cloves, and ½ teaspoon salt.
To make the caramel, combine granulated sugar and ⅓ cup water in a large heavy-bottomed saucepan set over medium heat and stir to combine. Cook until sugar melts, about 1 minute, then increase the heat to medium-high. Cook, swirling the pan every few minutes, until the syrup is a rich caramel color, 6 to 7 minutes. Remove from heat and carefully whisk in the heavy cream (the mixture will bubble). Return to heat and simmer, whisking constantly, until smooth and thickened, 7 to 8 minutes. Remove from heat and add remaining ½ teaspoon salt. Set aside two tablespoons of the caramel, then stir the rest into the pumpkin filling. Add the eggs and whisk to combine. Pour onto pie crust.
Bake, rotating halfway through, until golden brown and the center is just set, 25 to 30 minutes. Lower oven temperature to 325°F and continue baking until a toothpick inserted in the center of the pie comes out clean, 10 to 12 minutes more. Let cool to room temperature, then refrigerate overnight. Just before serving, top with toasted coconut and cut into squares. Drizzle with reserved caramel, and top with flaky salt.