1 tablespoon cornstarch mixed with 2 tablespoons cold water (for curd)
Powdered sugar for dusting
Instructions
Prepare the cookie dough: Cream the softened butter and 1/2 cup sugar in a bowl until light and fluffy. Beat in the egg yolk and vanilla extract.
In a separate bowl, whisk together the flour, salt, crushed lavender buds, and lemon zest. Gradually add the dry ingredients to the wet ingredients, mixing until just combined into a soft dough.
Chill the dough for at least 30 minutes.
Preheat your oven to 350°F (175°C). Line baking sheets with parchment paper.
Roll the chilled dough into 1-inch balls. Place them on the prepared sheets, leaving space between them.
Use your thumb or the back of a small measuring spoon to press a deep indentation into the center of each dough ball.
Bake for 12 to 15 minutes, or until the edges are lightly golden. Let the cookies cool completely on the baking sheet before moving them.
Prepare the lemon filling: In a small saucepan, whisk together the lemon juice, 1/2 cup sugar, and 2 egg yolks.
Cook over medium-low heat, stirring constantly, until the mixture thickens enough to coat the back of a spoon (about 5-7 minutes). Do not boil.
Remove from heat. Whisk in the 4 tablespoons of butter until melted and smooth.
Whisk in the cornstarch slurry and return the pan to low heat, stirring until the mixture thickens further, about 1 minute.
Remove the curd from the heat and press plastic wrap directly onto the surface to prevent a skin from forming. Cool completely.
Once the cookies are cool, spoon about 1 teaspoon of the cooled lemon curd into each thumbprint indentation.
Dust the finished cookies lightly with powdered sugar before serving.
Notes
Use only culinary-grade lavender; ornamental lavender may not be safe for consumption.
To get a softer cookie, do not overbake; remove them when the edges just begin to set.
If the dough becomes too soft while shaping, return it to the refrigerator for 10 minutes.