In a mixing bowl, combine flour, sugar, and chilled butter until the mixture resembles coarse crumbs. Press the crumbly dough into a tart pan and refrigerate for 30 minutes.

Whisk together eggs, sugar, lemon juice, and lavender in a large bowl until smooth. Pour the filling into the chilled crust.

Bake in a preheated oven at 350°F for 30–35 minutes until the filling is set and the top is light golden.

Let the tart cool at room temperature before garnishing with lavender sprigs or whipped cream and serving chilled.