01 - Combine flour, sugar, and salt in a bowl. Add cold, cubed butter and work in with fingertips or a pastry cutter until mixture resembles coarse crumbs.
02 - Add egg yolk and cold water; mix until dough just holds together. Shape into a disk, wrap in plastic, and chill for 30 minutes.
03 - Preheat oven to 350°F. Roll out chilled dough on a lightly floured surface to fit a 9-inch tart pan. Press dough into pan, trim excess, and prick base with a fork.
04 - Line pastry with parchment paper and fill with pie weights or dried beans. Bake for 15 minutes, remove weights and parchment, then bake another 8 to 10 minutes until golden. Allow to cool slightly.
05 - Whisk eggs and sugar until smooth. Add lemon juice, zest, heavy cream, and melted butter; whisk until fully incorporated.
06 - Pour filling into baked tart shell. Bake for 20 to 25 minutes until center is just set but still slightly wobbly.
07 - Cool tart to room temperature, then refrigerate at least 2 hours before serving.
08 - Dust with powdered sugar or garnish with lemon slices prior to serving.