Preheat oven to 350°F. Butter a 9-inch square baking pan and line with parchment paper.
In the bowl of a stand mixer fitted with a paddle attachment or in a large bowl with an electric hand mixer, beat the butter and sugar on medium high speed until light and creamy. Add the flour and salt and mix until combined.
Press the dough into the prepared baking pan and chill for 30 minutes. Bake until just beginning to turn golden brown, about 15-20 minutes. Let cool.
To make the filling:
Whisk together the eggs, sugar. lemon juice, lemon zest, and flour in a medium bowl. Pour into the cooled crust and bake for 5 minutes past when the middle has set (test this by giggling the pan, if the center does not move, it is set), or 30-35 minutes total.
Let cool for about 30 minutes, then use the parchment paper to lift the bars out of the pan and let cool completely on a wire rack.
To brûlée the lemon bars:
It's best to work in small batches, so slice them into servings first. Sprinkle sugar on a few bars at a time and use a kitchen torch to melt and caramelize it. You may also use your oven broiler, watching carefully to make sure they don't burn.
Brûlée right before serving for best results. Store lemon bars in the fridge.
Notes
Notes:
If you'd like to skip the bruleed topping (though you shouldn't), simply dust the bars with powdered sugar once they have cooled.
If you cannot find meyer lemons at your grocery store, you may substitute regular lemons. If you do, increase the sugar to 1 ⅓ cup.