Preheat Like a Pro: Preheat the oven to 350°F and line an 8x8-inch pan with parchment paper, leaving overhang for easy removal.
Make the Shortbread Crust: In a large bowl, cream together the softened butter and granulated sugar until smooth and fluffy. Mix in the vanilla extract. Add the flour and salt and mix until a soft dough forms. Press evenly into the prepared pan.
Bake the Crust: Bake the crust for 18 to 20 minutes until lightly golden and set but not browned.
Prepare the Lemon Filling: While the crust bakes, whisk the eggs in a medium bowl until smooth. Add the sugar and whisk until glossy. Whisk in the lemon juice, lemon zest, flour, and salt until fully combined and silky.
Bake the Lemon Bars: Reduce the oven temperature to 325°F. Pour the lemon filling over the hot crust and bake for 22 to 26 minutes until the center is just set with a slight jiggle.
Cool and Chill: Let the bars cool completely at room temperature, then refrigerate for at least 2 hours for clean slicing and perfect texture.
Finish and Serve: Dust generously with powdered sugar just before slicing and serving.