Prepare the Shortcrust Pastry
1-Mix flour, powdered sugar, and salt: Mix flour, powdered sugar, and salt.
2-Rub in cold butter until crumbly: Rub in cold butter until crumbly.
3-Add egg yolk and cold water, knead: Add egg yolk and cold water, knead into a smooth dough.
4-Wrap and refrigerate for 30 minutes: Wrap and refrigerate for 30 minutes.

Bake the Tartlet Shells
5-Preheat oven to 180°C (350°F): Preheat oven to 180°C (350°F).
6-Roll out the dough, cut into 6: Roll out the dough, cut into 6 circles, and fit into tartlet pans.
7-Prick with a fork, blind bake for: Prick with a fork, blind bake for 10 minutes, then bake for another 5 minutes.

Make the Frangipane
8-Cream butter and sugar until fluffy: Cream butter and sugar until fluffy.
9-Mix in the egg and vanilla extract: Mix in the egg and vanilla extract.
10-Fold in ground almonds and flour: Fold in ground almonds and flour.

Assemble & Bake
11-Fill tartlet shells with frangipane, smooth the: Fill tartlet shells with frangipane, smooth the tops.
12-Sprinkle with sliced almonds: Sprinkle with sliced almonds.
13-Bake for 15-20 minutes until golden brown: Bake for 15-20 minutes until golden brown.

Final Touches
14-Let cool completely before dusting with powdered: Let cool completely before dusting with powdered sugar.