Preheat your oven to 425°F (220°C).

Line a 9-by-13-inch baking dish with parchment paper or aluminum foil. Leave a little extra paper hanging over the sides to make removing the finished bars easier.

Set the prepared baking dish aside.

In a medium mixing bowl, combine the all-purpose flour and 1/4 cup granulated sugar.

Add the cold, cubed butter.

Using a pastry cutter or two forks, work the butter into the flour mixture until it resembles coarse crumbs.

You can also prepare the crust in a food processor by pulsing the ingredients together until the mixture reaches the desired crumbly consistency.

Transfer the shortbread mixture to the prepared baking dish.

Press it firmly and evenly across the bottom of the pan, making sure the mixture reaches all four corners.

Use the bottom of a measuring cup if you want a smooth, compact layer.

Set the crust aside while preparing the pumpkin filling.

In a large mixing bowl, combine the pumpkin puree, eggs, salt, pumpkin pie spice, and 2 cups granulated sugar.

Whisk or beat the ingredients together until smooth and well combined.

Slowly pour in the evaporated milk, stirring until the mixture becomes evenly blended.

The filling will look relatively thin at this stage, which is completely normal.

Carefully pour the pumpkin filling over the prepared shortbread crust.

Spread the mixture evenly if necessary.

Place the baking dish in the preheated oven.

Bake at 425°F for 15 minutes.

Without removing the baking dish from the oven, reduce the temperature to 350°F (175°C).

Continue baking for another 50–55 minutes, or until the pumpkin filling is set around the edges and the center has only a slight jiggle.

Avoid overbaking, as the filling will continue to firm up while cooling.

Step 7: Cool Completely

Remove the baking dish from the oven and place it on a wire rack.

Allow the dessert to cool completely in the pan.

Once cooled, cover the dish and refrigerate for at least 2 hours.

For the best texture and cleanest slices, refrigerate overnight.

Carefully lift the chilled dessert from the baking dish using the parchment paper or foil overhang.

Transfer it to a cutting board and slice into evenly sized squares.

Serve chilled with whipped cream and a light dusting of cinnamon, if desired.