01 - Pulse flour, powdered sugar, and salt in a food processor. Add butter and pulse until coarse crumbs form. Add egg yolk and pulse briefly. Gradually add ice water, one tablespoon at a time, until dough forms.
02 - Press dough into a 9-inch tart pan with removable bottom. Refrigerate for 30 minutes.
03 - Preheat oven to 375°F. Line crust with parchment and pie weights. Bake 15 minutes, remove weights, then bake 8 to 10 minutes until golden. Let cool slightly.
04 - Whisk sugar with citrus zest to release oils. Add eggs, citrus juice, cream, melted butter, and salt; whisk until smooth.
05 - Pour filling into warm crust. Bake at 325°F for 25-30 minutes until just set with slight center wobble.
06 - Allow tart to cool completely in pan. Refrigerate at least 2 hours before serving.
07 - Optionally decorate with whipped cream and fresh citrus slices or zest before serving.