A perfect balance of sweet and tart, these lemon bars, prepared in layers, require surprisingly little hands-on work. You’ll mix the buttery, shortbread crust and as that bakes, you’ll whisk together the creamy, citrus filling. When the crust’s baked through, spread the top layer over it, and bake for awhile longer, before letting the whole pan cool in the fridge. One simply but smart shortcut—lining the baking pan with crisscrossed sheets of parchment paper—makes lifting these bars out of the pan, chopping, and storing them a snap. Even better: The individual bars, wrapped or covered, will keep in the refrigerator for up to 3 days.