Ingredients
Method
Start by Browning the butter
- Place the butter in a medium saucepan and melt over medium heat, stirring occasionally. Once it melts, it will begin to sizzle and foam. Keep cooking and start to stir constantly for 3-4 minutes and you will start to see brown specks appear. Keep stirring until the butter becomes an amber brown color and has a nutty aroma. Be careful, it can go from brown to burned very quickly! Remove from heat immediately, and pour into a large mixing bowl. Allow to cool for 5 minutes.
Make the shortbread layer
- Preheat the oven to 325℉. Line a 9×13 inch baking dish with parchment paper, leaving an overhang on the sides to help you lift the finished bars out of the pan.
- To the brown butter, add the sugar, vanilla, and salt and whisk to combine. Using a spatula, fold in the flour. The dough will be thick and somewhat greasy. Press the dough into the prepared baking pan in an even layer. Poke the top of the crust all over with a fork (this is called docking and it helps the filling stick and prevents large air bubbles). Bake for 22-25 minutes. Keep the oven on once you take the crust out, we'll need it to bake the filling.
Make the filling
- While the crust cools a little, make the filling. Sift the flour and sugar into a large bowl and whisk to combine. Then, whisk in the eggs, lemon juice, elderflower liqueur, and salt until smooth.
- Pour the lemon filling over the slightly cooled crust and carefully return to the oven to bake for 25-30 minutes. The center should be set and shouldn't jiggle when the pan is tapped. There will be bubbles, that's ok! Allow the bars to cool in the pan at room temperature for 1 hour, before transferring to the fridge to chill (still in the pan) for 2 hours before you slice it.
Once cooled, slice and serve
- Once the bars are completely cooled and set, lift them out of the baking pan and place on a cutting board to cut into squares. Sift a layer of confectioners sugar on top if desired. Enjoy! Bars stay fresh sealed in the refrigerator for up to 4 days. They may absorb the confectioners sugar after they sit for a while, so just add a little more before you are ready to serve.