Cream butter, powdered sugar, salt, and vanilla.
Add egg and mix, then incorporate flour.
Roll between two sheets of parchment and chill 30 minutes.
Cut 6 strips for tartlet sides and circles (8 cm) for bottoms.
Line rings and assemble. Trim excess. Chill again 30 minutes.
Preheat oven to 160°C (convection).
Prick bases and bake for 15–20 minutes until golden. Cool.
Brush inside shells with melted white chocolate.