Start with the raspberry puree. Add the raspberries to a blender or food processor and blend until smooth. Strain through a sieve if desired to remove the seeds.

Transfer the puree to a small saucepan over low-medium heat. Simmer gently, stirring occasionally, until thick and reduced. You’ll need about 15 to 20 minutes to reach ¼ to ⅓ cup. Set aside to cool.

Preheat your oven to 325°F (160°C). Line a 9×13-inch pan with parchment paper, leaving an overhang for easy lifting later. Set aside.

In a bowl, whisk together the flour, sugar, cornstarch, and salt for the shortbread crust. Stir in the melted butter until you have a thick dough.

Press the dough into the bottom of the prepared pan, creating a slight lip around the edges to hold the filling. Bake for 20 to 25 minutes, or until the top looks set and lightly golden.

While the crust bakes, prepare the lemon raspberry layer. In a large bowl, whisk together the sugar and cornstarch until no lumps remain. Add the eggs and whisk until smooth.

Stir in the cooled raspberry reduction, then pour in the lemon juice. Mix gently until fully combined. The mixture will be liquid—don’t worry, it sets as it bakes.

Remove the crust from the oven and gently prick the surface with a fork, being careful not to go too deep. Pour the lemon raspberry mixture evenly over the hot crust.

Return to the oven and bake for 20 to 25 minutes, or until the top looks set and no longer jiggles in the center. Let cool at room temperature for at least 1 hour.

Transfer to the refrigerator and chill for at least 2 hours before slicing. This helps the layers firm up and ensures clean cuts.

When ready to serve, lift the bars from the pan using the parchment overhang. Slice with a sharp knife, wiping between each cut. Store in the fridge for up to 5 days.