Defrosting: defrost individual squares in the refrigerator for up to 2 hours, or until no longer frozen.Freezing: freeze leftover bars with pieces of parchment paper separating the individual squares in a freezer-safe container for up to 3 months.They are best consumed within the first day of making them but are still safe to eat and tasty until day 4. Refrigeration: store fully cooled bars covered in the fridge for up to 4 days.Wipe the knife between uses with a warm cloth if the filling sticks to the knife. The best and cleanest way to cut these bars is to use a clear and sharp knife. Then cover with an airtight cover until serving. Refrigerate the bars uncovered until they are entirely cooled. For best flavor and texture, make the bars up to 24 hours ahead of time. You certainly can make this recipe ahead of time. If serving these bars at a warm or outdoor event like a cookout or potluck, I recommend bringing them out right before serving and returning to the refrigerator shortly after Can you make this lemon bar recipe ahead of time? That being said, these bars don't do well sitting in heat or at room temperature for long periods of time. This keeps the filling firm and I even think the flavor tastes more lemony and bright when served cool. These bars are best served cold or just at room temperature. Serve these easy lemon bars anytime you're craving or the situation calls for a light and cooling dessert, like: You can tell that the lemon bars are done when the filling firms up and just barely jiggles when you nudge the pan with a potholder. Let them come to room temperature immediately after baking and then pop them in the refrigerator to cool them off entirely. Cool the bars completely before enjoying - the flavor and texture of these bars is the best when totally cooled.Line the baking dish with parchment paper - this will help the bars easily release from the pan.Use a ceramic or glass plan - the baking is more even and you don't have to worry about any metal interacting with the acid from the lemon juice.Sprinkle the finished bars with confectioner's sugar - this adds an extra sweetness to balance out the acid but also covers up any of the air bubbles that may rise to the top when baking.Use fresh lemon juice, or the juice of about 3 lemons, for this recipe. Fresh lemon juice is the best - you can't beat the bright and tart flavor of fresh lemons.I like to leave mine out in the sun until the butter is softened to a smooth and spreadable consistency. Use softened butter - ultra-soft butter (but not melted) is best for this recipe.