In a medium bowl, whisk together the flour and salt.
Cut in the cold, cubed butter using a pastry cutter or your fingers until the mixture resembles coarse crumbs.
Stir in the granulated sugar.
Add the egg yolk and ice water, one tablespoon at a time, until the dough comes together.
Form the dough into a disc, wrap it in plastic wrap, and refrigerate for at least 30 minutes.
Preheat your oven to 375°F (190°C).
On a lightly floured surface, roll out the chilled dough to about 1/8 inch thick.
Cut out circles of dough to fit into a muffin tin, about 3 inches in diameter.
Gently press the dough circles into the muffin tin cups, forming a small tart shell.
In a large bowl, combine the brown sugar, melted butter, eggs, flour, vanilla extract, and corn syrup or maple syrup. Mix until smooth.
If using, fold in the raisins or chopped pecans.
Spoon the filling into the prepared tart shells, filling each about 3/4 full.
Bake in the preheated oven for 20-25 minutes, or until the filling is set and the pastry is golden brown.
Allow the butter tarts to cool completely in the tin before removing.
Enjoy your meal!