Chocolate Highland Cookie Bars recipe, a Yummy, dangerous

Ok, this was a recipe that I actually got from a book. It was a Joane Fluke Hannah Swenson Mystery.  I'll include the recipe here:

CHOCOLATE HIGHLANDER COOKIE BARS

 Ingredients:

Shortbread:
1 C softened butter (2 sticks, 1 1/2 pound)
1/2 C powdered sugar (make sure there's no big lumps
1/4 t salt
 2 C flour

Chocolate top:
4 beaten eggs
1 C melted butter, cooled to room temp. (2 sticks, 1/2 pound)
1 C white sugar
1 t baking powder
1/4 t salt
1/2 C flour
2 1/2 C chocolate chips (measure before they're melted

1/3 C powdered (confectioner's) sugar to sprinkle on top of the desert

FIRST STEP:
Cream butter with 1/2 C powdered sugar and salt.  Add flour and mix well.  Pat it in a greased 9-inch by 13-inch pan with your fingers. (That's a standard cake pan.)

Bake at 350 degrees F.  for 15 min.  That makes the shortbread crust.  Remove from the oven.  (Don't turn off the oven!)


SECOND STEP:
Mix eggs with melted butter and white sugar.  Add baking powder, salt, and flour, and mix thoroughly.  (A hand mixer will do the job if you are tired of stirring.)  I used a hand mixer for the whole thing.

Melt the chocolate chips in a small double boiler, a pan over hot water on the stove, or nuke them for 3 minutes in the microwave on high.  (be sure to stir, chips may maintain their shape even after they're melted.)

Add the melted chocolate chips to your bowl and mix thoroughly.

Pour this mixture on top of the pan you just baked and make sure it covers all of the shortbread crust.  Stick it back in the oven and bake it for another 25 minutes.  Remove it from the oven and sprinkle on additional powdered sugar.

Let it cool thoroughly to set up.  Then cut into brownie size bars.