The deep richness of the plum layer elevates this shortbread. The cooked mixture may seem to be very thick but thins out with the juiciness of the plums.
3 cups sliced pitted plums
1/4 cup sugar
1 tsp grated lime zest
1 tbsp tapioca flour or cornstarch
1 3/4 cups all purpose flour
1/2 cup sugar
1/4 cup cornstarch
1 tsp ground cardamom
1 cup cold unsalted butter, cubed
Line an eight-inch-by-eight-inch baking dish with parchment paper, with overhang over all sides. This makes the shortbread easier to remove.
Combine 2 cups plums with sugar and lime zest in a pot. Bring to boil and cook until mixture is very juicy, about 2 minutes. Stir in tapioca flour and bring to boil. Cook and stir for 1 minute, remove from heat, then add in remaining plums. Cool mixture.
Preheat oven to 350 F.
Combine flour, sugar, cornstarch, cardamom and salt in a food processor. Pulse in butter until mixture begins to form clusters. Place half of the dough into the prepared baking dish. Firmly press into an even layer. Bake for 13 to 15 minutes or until pastry is a pale gold around the edges.
Top with plums. Roll or pat out the remaining dough and place over plums. Prick a few holes into the top.
Bake until top is golden and plums are bubbling around the edges, about 25-30 minutes
Chill until firm and cut into bars.