For the Tartlet Crust:
Preheat oven to 350°F (175°C). Combine flour, powdered sugar, and salt in a food processor. Add cold cubed butter and pulse until mixture resembles coarse crumbs. Add egg yolk and pulse again. Gradually add cold water, 1 tablespoon at a time, until dough forms. Wrap in plastic wrap and chill for 30 minutes. Roll dough out, cut into circles, and press into tartlet pans. Bake for 12-15 minutes until golden. Let cool.

1. For the Lemon Filling:
   Whisk egg yolks, sugar, lemon juice, and zest in a saucepan. Cook over medium heat until mixture thickens to custard consistency, about 8-10 minutes. Remove from heat, stir in butter and heavy cream if desired. Let cool slightly.
2. Assemble the Tartlets:
   Once crusts are cool, spoon lemon curd into each tart shell. Top with fresh raspberries and refrigerate for at least 1 hour to set.
3. Serve:
   Dust with powdered sugar before serving, if desired.