First, preheat your oven to 350°F (175°C), and line your 8x8 baking dish with parchment paper. This ensures easy cleanup later and helps the bars come out just right.
In a bowl, mix the softened butter, white sugar, and brown sugar. Once that’s well combined, add the flour and blend it all together until you have a crumbly dough.
Press the dough evenly into the bottom of the prepared dish. Pop it into the freezer for 10 minutes (this helps it hold its shape during baking). Then, bake it for 10 minutes and let it cool while you make the lemon filling.
While your crust is cooling, it’s time to focus on that bright lemony goodness! In a bowl, whisk together the eggs, lemon juice, lemon zest, and vanilla extract. Once those are nicely blended, add the sugar and flour, whisking until everything is incorporated.
Once the crust has cooled for about 20 minutes, pour the lemon mixture over it. Carefully place the dish back in the oven for about 25 minutes. The lemon filling should be set with a slight jiggle in the center. The top should have a light golden color – a perfect sign of readiness!
Remove your lemon bars from the oven, and let them cool completely at room temperature. After they’ve cooled, place the dish in the refrigerator for at least an hour. The bars need to chill before cutting – this gives the filling time to firm up.
Once chilled, sprinkle a light dusting of powdered sugar over the top of the bars. It’s the perfect sweet finish to balance the tart lemon flavor.
Cut into squares, serve, and prepare to be amazed by how delicious and refreshing these lemon bars are!