Easy Thin Mint Cookie Bars
Serves 24
10 mins prep
18 mins cook
60 mins total
These thick, fudgy, brownie-like cookie bars are topped with a chocolate mint coating that is inspired by Girl Scout thin mint cookies! If you love my cosmic brownie cookies, this uses a very similiar base dough!
Toppings:
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Preheat oven to 350°F.
Tip before starting! I will note that this is a thicker dough that is easiest to make with a stand mixer. If you only have a handheld mixer, you may just need to use a spatula to help mix the flour in.
In a large bowl, use an electric mixer on medium-high speed to cream softened ¾ cup unsalted butter (i.e. 1 ½ sticks), ¾ cup light brown sugar, and ¾ cup granulated sugar for 2 minutes until light and fluffy.
Add the 2 large eggs, 2 teaspoons vanilla extract, and 3 tablespoons light corn syrup and mix on low speed until combined. Scrape down the sides of the bowl so everything can combine.
Add in 1 teaspoon baking powder and ½ teaspoon salt and mix for another 5-10 seconds until combined.
Lastly, add ¾ cup dark cocoa powder and 2 ¼ cup all-purpose flour and mix on medium until combined.
Spray a light-colored metal 9×13 pan with cooking spray, then line pan with parchment paper, leaving a 2 inch overhang on each long side so that you will be able to lift the bars out of the pan.
Drop the dough into 1-tablespoon sized chunks into the prepared pan and spread until smooth on top.
Tip: This dough is a little sticky, so to help spread, I recommend spraying your hands with cookie spray or use place another piece of parchment paper on top and continue pressing down.
Bake bars at 350°F for 18-22 minutes, or until the center no longer looks wet. The center may look a tiny bit underdone but the bars will continue to bake in the hot pan when cooling.
Allow to fully cool before decorating.
To Make Chocolate Coating:
Add 1 cup semi-sweet chocolate chips and ¼ cup unsalted butter (i.e. ½ stick) to a small to medium-sized microwafe-safe bowl. Heat on 50% power for 30 second increments until full melted, stirring in between (even if nothing is melted the first few rounds, still stir it!). Microwaving on 50% power is important to melt the chocolate slowly to prevent from the chocolate seizing or burning.
Once melted, add in the ¼ teaspoon peppermint extract and stir. Before spreading, set aside about 2 tablespoons of chocolate for the drizzle.
Note that this coating isn't as liquidy as a ganache, it's a little firmer so that it hardens up well. That said, if your mixture looks too thick to spread, you can add 1 tablespoon of melted butter to help thin.
Spread melted chocolate over cooled cookie bars until tops and sides are covered. Spoon the [adjustable]2[/adjustable] tablespoons of reserved chocolate in a piping bag or ziploc bag with a tiny corner cut off, then drizzle over top for added presentation.
Allow chocolate to harden before cutting; it's best to refrigerate or freeze for 30 minutes to help set.
To get clean slices, fill a tall cup with hot water. In between cuts, dip the knife into the water and use a paper towel to dry it off. When cutting, don't "saw" the bars but rather press straight down and gently lift the knife.