After the wet ingredients are ready, I whisk together the flour, baking powder, and salt in a separate bowl. I used to skip this step and dump everything right in, but I learned the hard way that whisking prevents dry clumps and helps the bars bake evenly. Once combined, the dough becomes thick and soft—almost like sugar cookie dough but slightly lighter. I spread it into my parchment-lined pan, smoothing it all the way to the corners. It doesn’t look like much before baking, but trust me, it transforms in the oven.
I bake the bars until the edges look very lightly golden and the center appears set but still soft. One mistake I made early on was overbaking, thinking the bars needed to look fully firm in the oven. They don’t. They continue to set as they cool, and if you pull them out at the right moment, the texture is incredible—tender, soft, and buttery. I let the pan cool completely on a rack before adding any frosting, otherwise the frosting melts into the bars.
Once cooled, I whip the frosting until it’s creamy and smooth. I like to start with the butter, adding powdered sugar gradually with splashes of milk until it reaches the perfect spreadable consistency. The moment it hits the bars, it glides beautifully across the surface, not tearing or pulling at the cookie base. The final step—sprinkles!—is always my favorite because it instantly transforms the bars from simple to celebratory.
Pro Tips for Best Results
I tested this recipe three different ways before landing on my favorite technique, and one tip I learned is not to overmix the dough once the flour goes in. The more you mix, the denser the bars become. I stop the mixer as soon as I no longer see streaks of flour; this keeps the texture tender and soft.
Another important tip is measuring flour correctly. I used to scoop directly from the bag, which compacts the flour and leads to dry bars. Now I spoon the flour into my measuring cup and level it off with a knife. This small change made my bars noticeably softer and less crumbly.
For the frosting, I highly recommend using room-temperature butter. Cold butter creates lumps, and melted butter makes the frosting runny. Soft, room-temperature butter blends beautifully and gives you that perfect fluffy consistency. Also, add the milk gradually—just a teaspoon at a time—until it reaches the texture you prefer.
Finally, don’t slice the bars until the frosting has set slightly. I’ve rushed this step before and ended up with frosting smearing all over my knife. Letting the bars chill for 15 minutes in the refrigerator makes slicing clean and easy.
Common Mistakes to Avoid
One mistake I made the first time I baked these was spreading the dough unevenly in the pan. I didn’t realize how important even thickness was, and my bars baked unevenly—thin on one side, thick on the other. Always take a moment to level it out with a spatula.(See the next page below to continue…)