Preheat oven to 350 degrees. Combine ingredients in a food processor, adding butter one piece at a time until a dry dough forms. (you can also cut in butter with a fork). Be careful not to over mix. The dough should be crumbly.
Press dough into an 8x8 parchment lined baking dish. Bake for 12 minutes. Let rest 3 minutes before pouring the pumpkin pie filling on top.
Pumpkin Pie Filling:
Combine all ingredients in a bowl and mix well, ensuring there are no lumps. Pour mixture on top of the HOT shortbread crust and bake for 50-60 minutes, or until center is barely jiggly and batter no longer appears wet on top.
Pour pecan topping (see below) on top, return to oven and bake another 20 minutes.
Remove and let cool fully. Refrigerate 3 hours or overnight. Remove from pan and slice into bars. Serve with whipped cream if desired.
Heat the ingredients in a sauce pan over medium heat until butter is fully melted and sugar starts to caramelize; about 3-4 minutes.
Be sure to use cold butter when making the short bread crust - cut it in with a fork or just pulse a food processor until combined. Be careful not to over mix or the butter will melt;
The pecan caramel topping can be omitted if desired, however, I think it's one of the best parts of this recipe!
The pumpkin filling should only jiggle a little when done and no longer looks wet on top - it will continue to set as it cools.
The pumpkin pie filling can be made a couple days ahead of time if desired. Store in an airtight container in the fridge until you're ready to use it.