MAKES 2-3 DOZEN
When these tarts are made properly—that is, Grandma Vincent's way—the filling pours out, so eat them over a plate.
For the tart shells:
5 1/2 cups unbleached all-purpose flour
1 1/2 tsp. salt
1 lb. vegetable shortening, cut into pieces
1 tbsp. white vinegar
For the filling:
2 cups raisins
3 tbsp. unsalted butter, cut into pieces
2 cups packed brown sugar
1/2 cup pure maple syrup
1/4 cup light corn syrup
1 tsp. vanilla extract
1. For the tart shells: Sift together flour and salt into a large mixing bowl. Use a pastry cutter or 2 knives to work the vegetable shortening into flour until it resembles coarse meal; set aside. Whisk together egg, vinegar, and 1 cup cold water in a medium mixing bowl, then add to flour mixture and stir with a fork until dough just begins to hold together. Press dough into a rough ball, then transfer to a lightly floured surface. Give dough several quick kneads with the heel of your hand to form a smooth dough, then shape into a ball. Wrap dough in plastic and refrigerate for 1 hour or overnight.
2. For the filling: Put raisins in a medium saucepan, cover with cold water by 1'', and bring to a boil over high heat. Drain, then immediately transfer raisins to a medium bowl and add butter, brown sugar, maple syrup, and corn syrup; stir until butter melts and mixture is well combined. Set aside to cool for 3-4 minutes. Beat 1 of the eggs in a small bowl, then add to filling and mix well. Repeat with remaining 3 eggs. Stir in vanilla and set aside. Raisins will sink to bottom and need to be stirred up again when filling tarts.
3. Heat oven to 425°. Roll dough out on a lightly floured surface to a 1/4'' thickness. Use a 4'' round cookie cutter to cut out 24-36 rounds, gathering dough scraps into a ball and re-rolling as needed. Fit rounds into standard-size muffin tins, then fill each about three-quarters full with filling. Bake until crusts are lightly golden and filling is barely set, 10-14 minutes. Cool tarts, then lift out of tins with a knife.