I created these bar cookies as an alternative to the apple and pumpkin desserts so popular this time of year. Tart yet sweet, with an oat crust, walnut-brown sugar filling, and a hint of cinnamon and vanilla, they are perfect for early fall, when plums are still in season.
Crust
1 cup all-purpose flour
1/4 teaspoon salt
1/4 cup brown sugar
¼ cup oats
1/2 cup unsalted butter, slightly softened
½ teaspoon cinnamon
Filling
5 tablespoons butter, slightly softened
1/2 cup brown sugar
1 cup finely ground walnuts
1 egg
1/2 teaspoon vanilla
1/2 teaspoon cinnamon
Topping
7 small plums, diced.
¼ cup brown sugar, for sprinkling
1 tablespoon oats, for sprinkling
Preheat oven to 350 degrees F.
Prepare the crust: In the bowl of a food processor, combine brown sugar, butter, salt, and cinnamon. Process until smooth. Add flour and oats. Pulse until thoroughly combined. Remove mixture onto a lightly floured surface and knead several times to form a smooth dough. Press evenly into the bottom of a square baking pan. Bake for 10 minutes, until a very pale golden brown. Set aside to cool.
Prepare the filling: While the crust bakes, combine butter, brown sugar, walnuts, egg, vanilla, and cinnamon in the food processor bowl (no need to clean the bowl first!) Process until smooth. Spread filling evenly over crust. Add the toppings: scatter diced plums over the filling. Sprinkle on brown sugar and oats.
Bake for 35-40 minutes, until filling is set and plums become jelly-like. To store, refrigerate in an airtight container. The flavors taste stronger and more delicious the next day.