1. Preheat the Oven

Preheat your oven to 375°F (190°C). Grease a muffin tin or line it with paper liners.

2. Make the Pastry

• In a medium bowl, combine the flour and sugar.
• Cut in the chilled butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs.
• Add the egg yolk and just enough cold water to bring the dough together. Mix until a soft dough forms.

3. Roll Out and Shape the Dough

• Roll out the dough on a lightly floured surface to about ⅛-inch thickness.
• Cut into circles slightly larger than the muffin cups and press the dough circles into the prepared muffin cups.

4. Prepare the Filling

• In a bowl, whisk together the melted butter, brown sugar, corn syrup, eggs, vanilla, and salt until smooth.
• Stir in pecans or raisins if desired.

5. Fill and Bake the Tarts

• Spoon the filling into each prepared pastry shell, filling each about ¾ full.
• Bake for 15-20 minutes, or until the filling is set and the tops are golden brown.

6. Cool and Serve

Allow the tarts to cool in the muffin tin for about 10 minutes, then transfer to a wire rack to cool completely.