Step 1: Prepare & Cream. Preheat your oven to 350°F (175°C). In a small bowl, whisk together the flour, baking powder, baking soda, and salt; set aside. In a large mixing bowl, add the softened unsalted butter and granulated sugar. Use an electric mixer to beat them together on medium-high speed for 3-5 minutes, until the mixture is visibly light, fluffy, and pale in color. This essential creaming step incorporates air, contributing to the bars’ tender texture.

Step 2: Incorporate Wet Ingredients. To the creamed butter and sugar mixture, add the room temperature eggs, vanilla bean paste (or vanilla extract), almond extract, and softened full-fat cream cheese. Continue beating with the electric mixer until all these ingredients are thoroughly incorporated and the mixture is smooth and cohesive. Remember to scrape down the sides of the bowl as needed to ensure everything is evenly combined.

Step 3: Gradually Add Dry Ingredients. With your electric mixer set to low speed, slowly add the whisked dry ingredients (flour, baking powder, baking soda, salt) to the wet mixture. Mix only until no visible streaks of flour remain. It’s crucial not to overmix at this stage; overmixing can lead to tough, dry cookie bars. If you choose to add sprinkles to the dough, gently fold them in during this final mixing step with the last bit of dry ingredients.

Step 4: Do Not Overmix! This step is so important it deserves a special mention. Once the dry ingredients are added, stop mixing as soon as the flour is just incorporated into the wet ingredients. The dough should be soft but not overly sticky. Overmixing develops the gluten in the flour, which can result in a tougher, more cake-like texture rather than the desired soft and chewy sugar cookie bar.

Step 5: Prepare for Baking. Line a 9×13 inch baking pan with parchment paper, ensuring that there’s an overhang on two sides. This overhang will serve as convenient “handles” to easily lift the cooled cookie slab out of the pan later. Press the cookie dough evenly into the prepared pan. The dough might feel a little sticky; for easier handling, you can lightly spray your hands with a bit of cooking oil or place another piece of parchment paper over the dough and press it down with your hands or a rolling pin.

Step 6: Bake to Perfection. Bake the cookie bars in your preheated oven for approximately 17-22 minutes. The crucial indicator for doneness is when the edges turn a light golden brown and the center appears set, no longer wet or overly gooey. It’s perfectly normal and desirable for the very center to still seem a touch underdone; like brownies, these bars continue to set as they cool, ensuring a wonderfully soft and chewy interior. Overbaking is the enemy of chewiness! Once baked, remove the pan from the oven and allow the cookie bars to cool completely on a wire rack before attempting to frost them. This is vital for the frosting to set properly without melting.

Step 7: Prepare the Luscious Frosting. While your cookie bars cool completely, it’s time to prepare the delicious buttercream frosting. In a large mixing bowl, beat the softened butter with an electric mixer until it is smooth and creamy. Next, add the vanilla bean paste (or vanilla extract), sea salt, and almond extract, mixing until these are well incorporated. Gradually add 2 cups of powdered sugar, beating slowly until fully combined and smooth. Finally, begin adding the heavy cream, one tablespoon at a time, beating until the frosting reaches your desired creamy, fluffy, and easily spreadable consistency.

Step 8: Color and Customize the Frosting. Add green gel food coloring to achieve your desired festive shade. For the vibrant green shown in the photos, about 5 drops of green gel food coloring were used, but you can adjust this amount to your preference for a lighter or darker shade. If you are planning to pipe detailed Christmas trees or intricate designs, you may need to add a touch more heavy cream to ensure the frosting has a smoother, more pipeable consistency. (Keep in mind that if you’re making many piped trees, you might need to double the frosting recipe; see the “Recipe Notes” section for specific quantities).

Step 9: Frost and Cut Your Bars. There are two main ways to approach frosting and cutting:

For classic cookie bars: Once your cookie bars are completely cooled, simply frost the entire surface evenly with your prepared buttercream. Generously add extra holiday sprinkles over the top for a festive finish. Allow the buttercream to set slightly before cutting into squares or rectangles of your desired size.

For Christmas tree bars: Carefully remove the fully cooled cookie bars from the baking pan by gently pulling on the excess parchment paper overhang, using it as tabs. Slice off any uneven ends to create a neat rectangular slab. Then, slice the slab into even rows. From these rows, cut back and forth at a diagonal to create adorable triangle “tree” pieces.

Step 10: Decorate and Serve. Transfer your prepared buttercream frosting into a piping bag fitted with your desired piping tip (a star tip works wonderfully for creating a textured “tree branch” effect). Decorate your cookie bars by piping in rows, creating swirls, or getting as creative as you like! For the Christmas tree shapes, pipe green frosting in zigzag patterns to mimic branches, then adorn them with holiday sprinkles to resemble ornaments. Allow the frosting to set slightly before serving these festive and delicious treats!