Prep & Preheat: Preheat your oven to 350°F (180°C). Lightly grease an 8-inch square baking pan and line it with parchment paper, allowing some overhang on the sides for easy lifting later.
Craft the Base: In a food processor, combine all the Shortbread Base ingredients. Pulse 5 to 10 times until the mixture resembles coarse, wet sand. Pour this mixture into the prepared pan and press it down firmly and evenly, ensuring it reaches all corners.
Bake the Base: Bake the shortbread base for 20 minutes, or until its edges are lightly golden. Remove it from the oven immediately – do not let it cool down.
Prepare the Zesty Topping: While the base is baking, whisk together all the Lemon Curd Topping ingredients in a medium bowl until smooth and well combined.
Combine & Bake: Carefully pour the lemon curd mixture over the warm shortbread base in the pan. Return the pan to the oven and bake for another 20 minutes, or until the lemon topping is set but still slightly soft in the center. A tiny crack on the surface is perfectly normal!
Cool & Chill: Let the bars cool completely on your kitchen counter for about 1 hour. Then, transfer them to the refrigerator to chill and firm up for at least 2 hours.
Slice & Serve: Once thoroughly chilled, use the parchment paper overhang to lift the entire slab out of the pan. Slice into 16 delightful squares. For a pretty finish, dust with a sprinkle of powdered sugar just before serving. Enjoy your refreshing homemade lemon bars!