This tasty treat makes for the perfect snack to share with friends and family, or just as a late-night indulgence. With its crunchy outside and gooey inside, this bar is sure to satisfy any sweet tooth! It's easy to make, too; all you need are a few simple ingredients that you can find in your pantry and fridge.
Prepare a 9x13 pan by either using pan grease, spraying with baking spray or lightly coat with butter and flour. Preheat the oven on 350°F/175°C
In a large bowl or the bowl of a stand mixer, combine the butter and the brown sugar. Mix on medium speed (using the paddle attachment if using a stand mixer) until the butter and brown sugar become light and fluffy. Scrape down the sides of the bowl at least once. Mixing of the butter and brown sugar is very important in the recipe and the mixing will take 7-10 minutes to achieve the fluffy result. At first the mixture will be heavy and even crumbly, but after mixing for 5 minutes, you will start to see it lighten up and become fluffier.
With the mixer on low speed, add in one egg and mix until incorporated. Add in the vanilla extract.
In a medium bowl, combine the flour, salt, and baking powder. Mix well.
Add about ⅓ of the flour mixture to the wet ingredients and mix on medium speed until the flour is incorporated. Scrape down the sides of the bowl as needed. Repeat with the remaining flour mixture.
Add in the chocolate chips and either stir in by hand or put the mixer on low for about 30-60 seconds. Add in the walnuts if using and mix together.
Spoon or scoop the cookie mixture into the prepared 9x13 pan and spread out into an even layer. Bake in a preheated 350°F/175°C oven for 25 minutes.
When the baking time is up, the top should be a light golden color and look flaky. Remove the pan from the oven and place on a cooling rack. Allow to cool for a full 2 hours before cutting and serving.
Cut the congo bars into 40 equal pieces. Serve & Enjoy!
Make sure to mix the brown sugar and butter together until it becomes light and fluffy or the congo bars will be too dense and slightly crumbly. If you aren't serving the entire batch of congo bars, it's best to leave them uncut for storing the refrigerator or the freezer. This helps prevent them from drying out.