If you are substituting ingredients like Splenda for sugar, make sure to read the conversion chart on the bag of Splenda (or other). Also, plain yogurt can be substituted for sour cream but it's a matter of taste. I like the sour cream better.
In a small mixing bowl, stir together the butter & 2 Tbls sugar. Stir in cracker crumbe and 2 Tbls of finely chopped pecans.
Once combined, press into the bottom of a lightly greased (butter-flavored PAM is great!) 8x8x2 inch baking pan. Bake in the preheated oven for 10 minutes or until the crust is lightly browned. Watch carefully!
Set the crust aside and let cool to the touch.
In a medium bowl, stir together the egg, mashed sweet potatoes and sour cream.
Stir in the 1/4 Cup sugar, all of the flour and the pumpkin pie spice until smooth.
Add milk slowly, stirring until smooth. (I do this to keep it from splashing out of the bowl.)
Pour Sweet potato mix evenly over the crust and bake @ 350 degrees F for about 25 minutes or until an inserted knife comes clean.
Immediately sprinkle the remaining chopped nuts and press lightly into filling. Cool completely in the pan then chill.
Remove from refrigerator and cut into bars. Stores in the fridge up to 2 days or the freezer for 1 month.