I received this recipe from my sister - apparently, the recipe has been floating around the internet ever since Christina Tosi, the pastry chef at Momofuku in New York City appeared on Live with Regis and Kelly.

Once you've made the dough for the cookie bars, the dough is supposed to be refrigerated for up to an hour to prevent the cookie bars from spreading too much but if you're pressed for time, this step can be skipped.

(This recipe is adapted from the Live With Regis and Kelly website)

Ingredients:
1 3/4C all purpose flour
2 tsp. baking powder
1 tsp. baking soda
2 tsp. kosher salt
1 C (two sticks) unsalted butter
1 C granulated sugar
3/4 C light brown sugar
1 tbls. corn syrup (you can substitute honey or maple syrup for the corn syrup if preferred)
1 tsp. vanilla
2 large eggs
2 tbls. used coffee grounds
1 1/2 C any baking add-ins (chopped dark or white chocolate, chocolate covered raisins, chopped snickers bars or peanut butter cups, rice krispies cereal, etc.)
1 1/2 C your favorite snack foods (potato chips, pretzels, nuts, etc.)

Directions:
Preheat oven to 350 degrees. Line 9"x13"x2" baking pan with parchment paper.
In a medium bowl, sift together the flour, baking powder, baking soda, and salt. Set aside.
In a stand mixer with the paddle attachment, cream butter, sugars and corn syrup on medium high for 2 to 3 minutes until fluffy and pale yellow in color. Scrape sides of the mixing bowl with spatula during mixing process.
On a lower speed add eggs and vanilla to incorporate. Increase mixing speed to medium high and start a timer for 10 minutes. During this time the sugar granules will fully dissolve, the mixture will become an almost pale white color and your creamed mixture will double in size.
When time is up, on a lower speed, add the flour mixture. Mix 45 to 60 seconds just until your dough comes together and all remnants of dry ingredients have incorporated. Don't walk away from your mixer during this time or you may risk over-mixing the dough. Scrape down the sides of the mixing bowl with a spatula.
On low speed, add in the coffee grounds and your baking add-ins of choice. Mix together for 30 to 45 seconds until they evenly mix into the dough. Add in your favorite snack foods last, paddling again on low speed until they are just incorporated.
Spread batter in prepared pan. Sprinkle the top of the batter with about 1/2 tsp. of sea salt (optional). Bake for 30 to 35 minutes. Let cool in pan on a wire rack. Cut into bars when cooled to room temperature.