Combine crust flour, powdered sugar, and salt. Cut in cold butter until fine crumbs form, then mix in egg yolk and water only if needed.
Press the dough together, flatten, and refrigerate 30 minutes. Roll between parchment into an 11-inch circle and fit into the tart pan.
Trim excess, prick the base lightly, and chill 20 minutes. Heat the oven to 350°F (175°C) and set the tart pan on a baking sheet.
Line with parchment and weights. Bake 15 minutes, remove weights, and bake 8–10 minutes more until lightly golden.
Reduce heat to 325°F (165°C). Whisk eggs and sugar gently, then add lemon juice, zest, and cream. Strain into a pouring jug.
Pour into the warm shell and bake 20–25 minutes, until filling is set around the edge with a slight center wobble.
Cool on a rack for 1 hour, then refrigerate for at least 2 hours. Keep the tart level so the filling sets evenly.
Unmold by supporting the base carefully. Cut chilled wedges with a warm wiped knife and serve plain or with a small spoonful of whipped cream.
