Preheat oven to 375°F. Lightly grease a 12-cup muffin tin.
Whisk flour, sugar, and crust salt in a bowl. Cut in cold butter until pea-sized.
Drizzle in ice water and cider vinegar. Stir just until dough clumps together.
Press dough into a disk, wrap, and chill 20 minutes to relax and firm up.
Roll dough to about 1/8 inch thick. Cut 4-inch rounds and fit into muffin cups.
Chill the lined pan 10 minutes while you mix the filling.
Whisk brown sugar, maple syrup, melted butter, liquid eggs, vanilla, filling salt, and white vinegar until smooth.
Scatter raisins and pecans into shells if using. Fill each shell about two-thirds full with filling.
Bake 22–25 minutes, rotating once, until centers puff and edges are set and golden.
Cool 10 minutes in the pan, then lift out and cool fully on a rack before serving.