In a food processor, pulse the cold butter and shortening into the flour, brown sugar, and salt. Process until the mixture resembles pea-sized pieces.

Sprinkle the ice water over the mixture and toss with a fork until just combined. Do not overwork the dough; it should stick together without being tough.

Form the dough into two rounds about an inch thick. Wrap each in plastic wrap and refrigerate for about 30 minutes.

Roll out the chilled dough on a lightly floured surface. Use a 4-inch cutter to cut out rounds and fit them into muffin cups.

Chill the pastry in the fridge or freezer while preparing the filling. Cold pastry helps achieve a flakier crust.

In a bowl, combine all filling ingredients except the raisins and mix well.

Place a single layer of raisins at the bottom of each pastry-lined muffin cup.

Fill each cup about ⅔ full with the syrup mixture.

Bake on the bottom shelf of a preheated oven at 425°F for 12 to 15 minutes.

Allow tarts to cool completely on a wire rack before removing them from the pans.