These things are popular.  They are a regular sell out.  While the Costco cookies sit neglected and wan in their plastic shells, these are consumed like no other confection brought to the parent/teacher or bake sale table.

I love how easy they are to make.  They can be mixed with a spatula.  I can get a pan of these ready for the oven in less time than it takes to preheat the oven. Measuring is hardly needed if you have a 1 lb box of brown sugar. Serve them warm, serve them cold…whatever.  You’ll soon get over being shocked at how quickly a batch of cookies gets consumed that contains one full pound of brown sugar.

This is an adaptation of a recipe from the Cafe Beaujolais Cookbook by Margaret S. Fox. She called them “Congo Bars” and made them to sell during her college years. In case you’re curious, these are  the changes I made: I increased the butter a scad (mostly because I find measuring 3/4 C butter easier than 2/3 C butter); And like with other recipes I’ve fiddled with, I believe that chocolate chips should not be skimped. Accordingly, the chocolate chip quantity has been doubled.  Feel free to increase the advised quantity further.  The more the merrier.
Ingredients:

• 3/4 C Butter, Melted (1 and 1/2 sticks of butter)
• 1 Lb Dark Brown Sugar
• 3 Large Eggs
• 2-3/4 C All Purpose Flour
• 2-1/2 tsp. Baking Powder
• 1/2 tsp. Salt
• 2 C Semi Sweet Chocolate Chips
• 1 C Walnuts (optional)

To Do:

Preheat the oven to 325 degrees.  Stir the melted butter and the brown sugar together in a large bowl with a spatula.  It will look like an unappetizing oily mess.
Next crack and stir in the eggs until combined. It’ll still look sludgey.
Dump the flour, baking powder, and salt on top of the wet mixture, and stir in until smooth.
Mix in the chocolate chips, and nuts (if using)Spread in a non stick sprayed 12 1/2 x 17 1/2 x 1 jelly roll pan. The mixture will be sticky and might not look like it’ll spread out in the pan, but it does,
Bake in a preheated 325 degree oven for about 25 minutes or until the top is just browned and a little puffed.
Do not overbake these if you want soft blondies. The puffiness will sink down after you remove the sheet from the oven. 
Cut into squares, triangles, or diamonds, while the blondies are warm. They get considerably harder to cut after completely cool.   Makes 1 to 60 servings. It all depends.