18 (1 1/2-inch) tarts
1/3 cup butter
1 cup brown sugar
2 tablespoons milk
1/2 cup raisins
1 vanilla bean
Combine the flour, salt, and sugar in a mixing bowl. Add the lemon zest and vanilla. Cut in the butter and mix until the butter is in pea-sized pieces. Add the eggs and water and mix until combined. Divide the dough into 18 pieces and roll each into a circle. Press the dough into tart pans.
Filling: Melt the butter, brown sugar and milk in saucepan and stir until the sugar starts to dissolve. Take the pan off the heat and whisk in the egg and raisins.
Preheat the oven to 350 degrees F. Bake the tart crusts for 12 minutes. Divide the filling among the tarts and bake until bubbly, about 5 minutes.