📖 Instructions

1. First things first, let's get that oven ready to go! Preheat your oven to 350°F (175°C). This ensures everything bakes evenly from the moment it hits the heat. While it’s heating up, grab an 8x8-inch baking pan and line it with parchment paper, making sure to leave an overhang on two sides. This little trick is a game-changer for lifting the bars out easily later. If you don't have parchment, lightly grease and flour the pan, but trust me, parchment is easier!
2. Now for the crust! In a medium mixing bowl, combine 1 cup (2 sticks) of softened, unsalted butter with 1/2 cup of granulated sugar and a pinch of salt. Use an electric mixer, or even just a sturdy whisk and some elbow grease, to cream them together until they're light and fluffy. This should take about 2-3 minutes. You want it to look pale yellow and airy, not dense. Add in 2 cups of all-purpose flour gradually, mixing on low speed until just combined. The mixture will look crumbly, almost like wet sand, but don't worry, that's exactly what we're after. Be careful not to overmix here; overmixing can make your crust tough.
3. Press the crust into your prepared 8x8-inch baking pan. Use the back of a spoon, your clean hands, or even the bottom of a flat glass to press it down firmly and evenly into the bottom of the pan. Make sure it goes all the way into the corners so you don't have any thin spots. This is your foundation, so make it solid! Bake this crust for 18-20 minutes, or until the edges are just barely golden. It should smell wonderfully buttery. Take it out of the oven and set it aside to cool slightly while you prepare the lemon filling. Keep the oven on!
4. Time for the glorious lemon filling! In a separate medium mixing bowl, whisk together 4 large eggs until they're lightly beaten. Add in 1 1/2 cups of granulated sugar, 1/4 cup of all-purpose flour, 1/2 teaspoon of baking powder, and a generous pinch of salt. Whisk everything together until it's smooth and lump-free. Don't be afraid to give it a good, vigorous whisk! Now, for the star of the show: the lemon. Add 1/2 cup of fresh lemon juice (that's usually 2-3 juicy lemons, so make sure you've got them!). If you want an even bigger lemon punch, add a tablespoon of fresh lemon zest too – this really brightens the flavor. Whisk again until everything is perfectly combined. The mixture will be quite thin, almost like a thin batter. That's okay!
5. Carefully pour the lemon filling over the warm, partially baked shortbread crust. You can leave the pan on the counter, just pour slowly and evenly. Return the pan to the oven and bake for another 20-25 minutes. How do you know it's done? The edges of the lemon filling should be set, but the center might still have a slight jiggle to it when you gently shake the pan. The top might also develop a very light, delicate golden color. Avoid overbaking, as this can make the lemon filling rubbery. We want that perfect, smooth, custardy texture.
6. Once baked, take the pan out of the oven and place it on a wire rack to cool completely. And I mean *completely*! This is crucial, my friends. As it cools, the lemon filling will set up properly. If you try to cut into it while it's still warm, it will be messy and gooey. Patience is a virtue here! Once it's at room temperature, pop the whole pan into the refrigerator for at least 1-2 hours, or even better, overnight. Chilling makes it much easier to cut and also enhances the refreshing quality of the lemon.
7. When thoroughly chilled, use the parchment paper overhangs to carefully lift the entire slab of lemon bars out of the pan and onto a cutting board. Discard the parchment. Using a sharp, thin knife, slice the bars into squares. I like to wipe my knife clean between cuts for super neat edges. For that classic finish, dust the cooled, cut lemon bars generously with powdered sugar just before serving. You can use a small sieve for an even, delicate coating. Enjoy your bright and zesty homemade treat! Any leftovers can be stored in an airtight container in the refrigerator for up to 3-4 days.