For the Crust:

1. Preheat the oven to 350 degrees F.  Line an 8 x 8-inch baking pan with parchment paper and set it aside.
2. Combine all the ingredients and press them into the pan.  Place the pan in the oven and bake for 10 minutes or until the edges just begin to brown.

Prepare the Filling:

1. Beat together the egg yolks and allulose until very thick, about 3-4 minutes.  Slowly add in the sweetened condensed milk while mixing.  Add in the lemon juice and zest (or extract) and mix until combined. 
2. Pour filling over crust and bake for 12-15 minutes or until the filling is just set.  Remove from oven and allow to cool fully, about 4 hours.

Prepare the Whipped Topping:

1. Beat together the cold cream and sweetener until light and fluffy.  Spread the whipped topping over the bars and decorate with lemon zest or lemon slices.  Keep bars refrigerated.