A buttery and sweet crust made from shortbread cookies makes this tart unique. A simple recipe of lemon juice, eggs, and sugar creates an incredibly easy custard, and the raspberry and thyme sauce is the perfect finish.
In a food processor, pulse the shortbreads until they are finely ground. Transfer to a bowl and add the melted butter. Mix together to coat the crushed shortbread, then press into the bottom of a tart pan. Transfer the pan to the refrigerator as you assemble the filling.
Preheat the oven to 300 degrees.
In a saucepan, whisk together the lemon juice, zest, sugar, eggs, and salt. Heat up over medium heat, and cook, continuing to whisk, until the mixture is thickened- about 12-15 minutes. Remove from heat and add the pats of butter 1 at a time, stirring to combine. Pour the lemon filling into the prepared tart pan, and bake until the curd is set- about 15-25 minutes. Let completely cool before cutting.
While allowing the tart to cool, make the sauce.
In a small sauce pan, combine raspberries, thyme, and sugar, and heat over medium heat. Cook until raspberries have broken down, about 5-7 minutes. Strain through a fine-mesh strainer over a small bowl, using a spoon to push against the pulp to get all the juice out. Discard pulp.
Cut lemon tart into slices, and garnish with the raspberry-thyme sauce.