For the Shortcrust Pastry:

1. Make the pastry dough: In a large bowl, combine flour and powdered sugar. Add cubed cold butter and rub into the mixture with your fingers until it resembles breadcrumbs. Add egg yolk and 2 tablespoons of cold water. Mix until the dough comes together, adding more water if needed.

2. Chill the dough: Form the dough into a ball, wrap it in plastic wrap, and refrigerate for 30 minutes.

3. Roll out the dough: Roll the dough to 1/8-inch thickness on a floured surface. Cut out circles to fit your tartlet pans.

4. Line the pans: Press the dough into tartlet pans, ensuring they cover the base and sides. Prick the bottoms with a fork to prevent puffing up. Chill for 15 minutes.

5. Bake the pastry: Preheat the oven to 350°F (175°C). Bake tartlet shells for 12-15 minutes until golden. Cool completely.

For the Lemon Curd:

1. Prepare the lemon curd: Whisk egg yolks, sugar, lemon juice, and zest in a saucepan over medium heat, whisking constantly until the mixture thickens (about 5-7 minutes). Be careful not to let it boil.

2. Finish the curd: Remove from heat and stir in butter until smooth. Cool to room temperature.

For the Decoration:

1. Prepare the whipped cream: Whip cream with powdered sugar until stiff peaks form.

2. Assemble the tartlets: Spoon or pipe lemon curd into the cooled tartlet shells.

3. Decorate with whipped cream: Pipe whipped cream around the edges in a daisy shape and add a dollop of lemon curd in the center.

4. Finish with powdered sugar: Dust with powdered sugar for a beautiful finish.

5. Serve and enjoy: Serve immediately or refrigerate for up to 2 hours before serving.