Lemon Curd:

1. Make the lemon curd first.
2. In a saucepan whisk together the sugar and the egg until smooth.
3. Stir in the melted butter, fresh lemon juice, and lemon zest, and cook on low-medium heat, whisking often.
4. Whisk and cook until the lemon curd glaze thickens, about 15 – 20 minutes.

Shortbread Crust:

1. Preheat your oven to 375 degrees.
2. Line an 8-inch square baking dish with parchment paper, making sure to leave some overhang so you can pull the square easily out once it’s done baking.
3. In a bowl whisk together the flour, sugar and salt.
4. Add the butter, and with a pasty cutter or your hands, work the butter into the flour until it is a crumbly dough.
5. Measure out about 2 tablespoons of the dough for the crumble topping, and refrigerate.
6. Then press the remaining dough into the baking pan.
7. Put the pan into the freezer for about 10 minutes to make the dough firm.
8. Then bake the dough for 15 minutes.
9. Remove from the oven and spread on the lemon curd, making sure to leave a border about a 1/2 inch wide.
10. Crumble on the 2 tbsp of remaining refrigerated dough.
11. Return the square to the oven and bake for about 20 minutes, or until the edges are golden brown.
12. Let the baked square cool for at least 20 minutes, then using the parchment overhang lift it out of the pan and cut into squares.