Peppermint Sugar Cookie Bars

• 2¾ cups all-purpose flour
• 1 teaspoon baking powder
• ½ teaspoon baking soda
• ½ teaspoon salt
• 1 cup unsalted butter, softened
• 1½ cups granulated sugar
• ½ cup powdered sugar
• 1 large egg
• 1 teaspoon vanilla extract
• 1 teaspoon peppermint extract​

Peppermint frosting

• 1 cup unsalted butter, softened
• 3 cups powdered sugar
• ¼ cup heavy cream (or milk), plus more as needed
• 1 teaspoon vanilla extract
• ½ teaspoon peppermint extract
• Crushed peppermint candies or candy canes, for topping​

Step-by-Step Instructions

Make the cookie bar base

1. Preheat oven to 350°F (175°C). Grease a 9×13-inch baking pan or line it with parchment paper, leaving overhang on the sides for easy lifting later.​
2. In a medium bowl, whisk together flour, baking powder, baking soda, and salt until evenly combined. Set aside.
3. In a large mixing bowl, cream the softened butter, granulated sugar, and powdered sugar together for 2–3 minutes, until light, pale, and fluffy. Proper creaming incorporates air for a softer bar texture.​
4. Beat in the egg, vanilla extract, and peppermint extract until smooth and fully combined.
5. Gradually add the dry ingredient mixture to the wet ingredients, mixing on low speed just until no dry streaks remain. Avoid overmixing, which can lead to dense bars.

Bake the cookie bars

6. Spread the cookie dough evenly into the prepared 9×13-inch pan, smoothing the surface with a spatula so it’s an even thickness across the pan.​
7. Bake for 20–25 minutes, or until the edges are lightly golden and a toothpick inserted in the center comes out clean or with a few moist crumbs.
8. Remove the pan from the oven and let the bars cool completely in the pan on a wire rack. Cooling fully is essential so the frosting doesn’t melt or slide off.

Make the peppermint frosting

9. In a large bowl, beat the softened butter until smooth and creamy.
10. Gradually add powdered sugar, mixing on low at first and then increasing speed, until the mixture is thick and fluffy.
11. Mix in the vanilla and peppermint extracts.
12. Add the heavy cream (or milk) a little at a time, beating until the frosting is smooth, creamy, and easily spreadable. Adjust with a bit more cream for a softer frosting or more powdered sugar for a stiffer one, as done in similar peppermint buttercream recipes.​

Frost, decorate, and slice

13. Once the cookie bars are completely cool, spread the peppermint frosting evenly over the surface with an offset spatula.
14. Immediately sprinkle crushed peppermint candies or candy canes over the frosting, pressing very lightly so they adhere.​
15. For the cleanest cuts, chill briefly to firm the frosting, then lift the slab from the pan using the parchment overhang and cut into bars or squares.
    
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