Creamy Frosted Sugar Cookie Squares

1. Preheat Oven and Prepare Pan

First, preheat your oven to 350 degrees Fahrenheit. While the oven is warming up, butter a 9-by-13-inch baking pan and then line it with parchment paper. This will make it easier to remove the bars later.

2. Mix Dry Ingredients

In a medium bowl, whisk together the flour and fine sea salt. This step helps to evenly distribute the salt throughout the flour.

3. Beat Butter and Cream Cheese

In a large bowl, using an electric mixer or a stand mixer fitted with the paddle attachment, beat 1 cup of unsalted butter and the cream cheese together at medium speed for about one minute. The mixture should become light and fluffy, which means the butter and cream cheese are well combined.

4. Add Sugar

Next, add the granulated sugar to the butter and cream cheese mixture. Beat everything together for another minute until it looks creamy and smooth.

5. Add Egg and Vanilla

Now, add the egg and 2 teaspoons of vanilla extract to the mixture. Beat again for about one minute, ensuring everything is fully incorporated.

6. Combine Dry and Wet Ingredients

Gradually add the flour mixture to the wet ingredients, mixing on low speed until everything is just combined. This ensures the dough is well-blended without overmixing, which helps to create a tender crumb in your cookie squares.

7. Bake the Dough

Scrape the dough into your prepared baking pan and spread it out evenly with a spatula. Smooth the top as best as you can. Bake in the preheated oven for 20 to 25 minutes, or until the edges are light golden brown and a toothpick inserted into the center comes out with moist crumbs. The bars should be moist and slightly underbaked in the middle, which keeps them soft.

8. Cool the Cookie Slab

Once baked, set the pan on a wire rack to cool completely. Once cooled, you can easily remove the cookie slab from the pan by lifting the parchment paper.

9. Prepare the Frosting

For the frosting, beat the remaining 6 tablespoons of unsalted butter in a stand mixer fitted with the paddle attachment for about one minute, until it becomes smooth and creamy. Gradually add the confectioners’ sugar, beating until fully incorporated. This step might require two iterations to avoid a sugar cloud in your kitchen.

10. Add Liquid Ingredients to Frosting

Add the tablespoon of milk or heavy cream, the lemon juice, 1 teaspoon of vanilla extract, and 1/4 teaspoon of fine sea salt to the frosting. Beat everything together for about four minutes until the frosting is light and fluffy. If you want to add some color, mix in a drop or two of gel food coloring.

11. Adjust Frosting Consistency

If the frosting is too thick or too thin, adjust the consistency by adding a little more milk, lemon juice, or vanilla extract, beating after each addition until you achieve the desired consistency.

12. Frost the Cookie Slab

Spread the frosting evenly over the cooled cookie slab, and if desired, decorate with assorted sprinkles.

13. Cut and Serve

Finally, cut the frosted cookie slab into 20 bars and serve. Enjoy your creamy frosted sugar cookie squares!