Preheat your oven to 375 degrees F. While the oven is heating, grab a 9x13 pan (a glass Pyrex dish works great) and spray it with cooking spray. This will prevent the bars from sticking.
In a medium bowl, whisk together the all-purpose flour, baking powder, and salt until well combined. This dry mixture will give the bars their structure.
In a small bowl, mix the granulated sugar and lemon zest. Using your fingers, rub them together until fragrant. This step releases the essential oils from the zest, enhancing the lemon flavor.
In the bowl of a stand mixer, combine the butter and the lemon-sugar mixture. Beat on medium speed until smooth and fluffy, about 3 minutes. This creates a light base for your bars.
Slowly add the powdered sugar to the mixture, continuing to beat until it becomes light and fluffy. You'll want a creamy texture at this point.
Next, add in the eggs, lemon juice, and vanilla extract. Beat until the mixture is smooth and well combined, ensuring everything is evenly incorporated.
Gradually add the flour mixture to the wet ingredients, mixing at a low speed until just combined. Be careful not to overmix; you want the dough to be tender.
Spread the cookie dough evenly into the prepared pan using a spatula. Make sure it’s smooth and even for consistent baking.
Bake in the preheated oven for 12 to 14 minutes. You want the bars to be set in the middle but not browned. Check for doneness by gently pressing the center; it should spring back.
Once baked, remove the pan from the oven and let the bars cool completely in the pan.
While the bars are cooling, prepare the lemon cream cheese frosting. In the stand mixer, beat together the butter and cream cheese until smooth and creamy.
Add the lemon zest and lemon juice, mixing until combined. Gradually add the powdered sugar, one cup at a time, until the frosting is smooth and fluffy.
Once the cookie bars are completely cool, frost them generously with the lemon cream cheese frosting. Feel free to use as much or as little as you like!
For an extra touch, decorate with colored sugar or sprinkles. Finally, cut the bars into squares and serve. Enjoy your delicious Lemon Sugar Cookie Bars!
Make sure to store any leftovers in an airtight container in the fridge for up to two days. They stay delicious and fresh!
