Preheat your oven to 350°F, then line an 8x8 inch baking pan with parchment paper, leaving some overhang for easy removal.
In a medium bowl, combine flour, sugar, salt, and softened butter. Mix until it soft dough forms.
1 cup all-purpose flour, 1/4 cup granulated sugar, 1/2 cup unsalted butter, 1/4 teaspoon salt
Press the dough evenly into the bottom of the prepared pan then bake in the preheated oven for 15-18 minutes or until lightly golden brown.
Make the Pumpkin Pie Filling While the Crust is Baking
In a bowl, whisk together the pumpkin puree, brown sugar, granulated sugar, egg, vanilla, cinnamon, ginger, nutmeg, cloves, and salt until smooth.
15 oz pumpkin puree, 1/2 cup brown sugar, 1/4 cup granulated sugar, 2 large egg, 1 teaspoon vanilla extract, 1 teaspoon cornstarch, 1 & 1/2 teaspoon ground cinnamon, 1/2 teaspoon ground ginger, 1/4 teaspoon ground nutmeg, 1/4 teaspoon ground cloves, 1/2 teaspoon salt
Stir in the evaporated milk (or heavy cream) until well combined.
12 oz evaporated milk
Pour the pumpkin filling over the hot pre-baked shortbread crust.
Bake for 45-50 minutes, or until the filling is set in the outside and slightly jiggly in the center or a toothpick inserted into the center comes out mostly clean.
Allow the bars to cool completely in the pan, before chilling them in the fridge for a few hours to set for at least 2 hours.
Once cooled, lift the bars out using the parchment paper and cut into squares. Top with whipped cream and enjoy!
Notes
To make these in a 9x13 pan: double every ingredient. Bake the crust 18 to 20 minutes, then bake the filling 50 to 60 minutes, checking at 50. A 9x13 is a little under twice the area of an 8x8, so a straight double keeps the custard the same depth. Makes 18 to 24 bars.Doneness: the edges should be set with a slight jiggle in the center. Liquid pooling on top means they've overbaked.Storage: airtight in the fridge up to 4 days, or wrapped individually in the freezer up to 3 months.