Add the raspberries to a blender or food processor and blend until smooth.

Pour the puree through a fine mesh sieve to remove the seeds if desired.

Transfer the strained puree to a small saucepan.

Simmer over low-medium heat for 15–20 minutes, stirring occasionally, until reduced and thickened.

You should have approximately ¼ to ⅓ cup of concentrated puree.

Remove from heat and allow to cool.

Preheat the oven to 325°F (160°C).

Line a 9×13-inch baking pan with parchment paper, leaving an overhang on the sides.

In a medium bowl, whisk together flour, sugar, cornstarch, and salt.

Stir in the melted butter until a thick dough forms.

Press the dough evenly into the prepared pan and slightly up the edges.

Bake for 20–25 minutes until lightly golden and set.

Remove from the oven and gently prick the surface with a fork without piercing all the way through.

While the crust bakes, whisk together sugar and cornstarch in a large bowl.

Add the eggs and whisk until smooth.

Whisk in the cooled reduced raspberry puree.

Slowly whisk in the fresh lemon juice.

Pour the Lemon Raspberry Bars filling over the warm baked crust.

Return to the oven and bake for 20–25 minutes until the top is set.

Remove from the oven and cool in the pan for at least 1 hour.

Cover and refrigerate for at least 2 additional hours.

Lift the bars from the pan using the parchment overhang.

Slice with a sharp knife, wiping the blade clean between cuts for neat edges.