Once the dough base is rock-solid, I decide on the finish. Sometimes, for a simple look, I just dust the top liberally with powdered sugar using a fine-mesh sieve. But for the full festive effect, I make the easy vanilla frosting. I beat the softened butter, powdered sugar, vanilla, and milk together until it’s smooth and spreadable. I slather it over the chilled base, scatter on a blizzard of colorful sprinkles, and then return the pan to the fridge for another 30 minutes to let the frosting set. Finally, I use the parchment paper “handles” to lift the entire slab onto a cutting board for slicing.
Pro Tips for Best Results
The temperature of your melted butter is more important than you think. I tested this with boiling hot butter, warm butter, and cooled butter. Using butter that’s just barely warm to the touch (melted and then rested for 10 minutes) gave me the perfect dough consistency. Boiling hot butter made the dough greasy and difficult to work with, while cooled butter didn’t blend with the sugars as smoothly. Aim for that sweet spot of liquid but not hot.
When pressing the dough into the pan, don’t be shy. A firmly packed base is essential for bars that don’t crumble when you bite into them. I use a small piece of parchment paper placed directly on the dough and press with the measuring cup on top of that. This prevents sticking and allows me to apply serious, even pressure without making a mess. A loosely pressed base will yield a crumbly, messy bar.
For the frosting, if you’re using it, consistency is everything. You want it thick enough to hold its shape and not soak into the bar, but spreadable enough to create a smooth layer. If it’s too thin, add more powdered sugar. If it’s too thick, add milk a half-teaspoon at a time. I always frost the bars while the base is cold from the fridge. A cold base helps the frosting set quickly and cleanly.
Common Mistakes to Avoid
The biggest mistake is not measuring the flour correctly. Scooping the flour directly from the bag with your measuring cup packs it in, leading to an excess of dry ingredients. This will give you a dry, crumbly dough that’s impossible to press. Always spoon the flour lightly into your measuring cup and level it off with a knife. I made this mistake the first time and ended up with a sandy, powdery mess that wouldn’t hold together—don’t do what I did!(See the next page below to continue…)