Shortbread

• 227g (2 sticks / 1 cup) unsalted butter, melted and slightly cooled
• 100g (½ cup) granulated sugar
• 1 ½ tbsp lemon zest (from 2 lemons)
• 280g (2 cups) all-purpose flour
• ½ tsp salt
• 2 tsp pure vanilla extract

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Lemon Custard

• 4 large egg yolks
• 150g (¾ cup) granulated sugar
• 1 ½ tbsp lemon zest (from 2 lemons)
• 40g (¼ cup) cornstarch
• Pinch of salt
• ¾ cup lemon juice (from 4 lemons)
• 1 ¼ cups whipping cream (35%)
• 1 ¼ cups whole milk (3.25%)
• 2 tbsp (28g) unsalted butter, room temperature

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Topping

• 100g (1/2 cup) granulated sugar

1. Place the oven rack in the middle of the oven.
2. Preheat the oven to 350°F.
3. Butter a 9-inch square pan and line with parchment paper.  Leave an overhang to use as a sling to remove the lemon bars from the pan.  Set aside.
4. Shortbread: Rub the lemon zest into the granulated sugar with your fingers, in a large bowl.  This important step releases more oils.
5. Whisk in the flour and salt until incorporated.
6. Pour the vanilla and butter into the bowl and stir with a spatula until well combined.
7. Transfer the dough to the prepared pan.
8. Use your fingertips to gently press the shortbread into the bottom of the pan.
9. Use a small offset spatula to evenly smooth out the shortbread.
10. Bake the shortbread for 20 minutes.  The edges should be golden brown.
11. Use a fork to poke holes all over the warm shortbread.  Be careful not to poke all the way through to the bottom of the pan.  This step helps the lemon custard hold onto the shortbread crust.
12. Lemon custard: Place the 2 tablespoons of butter in a large bowl.  Place a fine mesh strainer over the bowl.  Set aside. 
13. Whisk the egg yolks, sugar, lemon zest, cornstarch and salt together in a medium saucepan.
14. Slowly pour the lemon juice into the saucepan, whisking constantly.
15. Pour the cream and milk into the saucepan, whisking constantly.
16. Cook the custard over low heat while whisking constantly (you can also use a silicone spatula) to ensure it doesn’t stick to the bottom of the saucepan.  The mixture will thicken and eventually start to bubble.  This step took me 20 minutes (cooking time might differ based on the heat of your element and the size of your saucepan, so always keep an eye on the custard).
17. Once you’ve reached the right consistency and the bubbles stage, remove the saucepan from the heat.
18. Pour the lemon custard into the fine mesh strainer that is set over the bowl containing the butter.  This step’s purpose is to remove the lemon zest from the custard.
19. Whisk or stir the lemon custard to incorporate the butter.
20. Pour the hot lemon custard over the warm shortbread.
21. Use a small offset spatula to spread the custard evenly.
22. Return the pan to the oven and bake for 14 minutes.  The custard’s top will have set and bubbles  will start appearing on the edges.
23. Remove the pan from the oven and let the bars cool to room temperature in the pan.
24. Cover the pan with aluminium foil or plastic wrap.  Transfer the pan to the fridge to chill for 8 hours or overnight.
25.  Slice the chilled bars into 16 squares.
26. Sprinkle a couple squares at a time with granulated sugar.  Only do this step when you are ready to serve the dessert.
27. Use a small blowtorch to caramelise the sugar.
28. Let the lemon brûlée bars rest for a few minutes to ensure the caramelised sugar has time to harden.
29. Pick up a spoon and snap that crackly lemon brûlée bar!