These bar cookies are easy to make and don’t have to be refrigerated after baking. One note of caution: do not use frozen blueberries! They will turn to mush and take the cookies with them. If fresh blueberries are not available, just skip them. The cookies are good with just the preserves.
1 stick butter, melted and cooled
1 extra large egg, room temperature
1 18 oz box lemon flavored cake mix
1 cup blueberry jam or preserves
1 cup fresh blueberries
2 Tbsp powdered sugar
1. Preheat the oven to 350° and lightly grease a 9×13″ baking dish.
2. In a large bowl, blend together the cooled melted butter and room temperature egg. (Both must be close to the same temp to avoid scrambled eggs.) Blend in the cake mix to form a stiff batter with no dry pockets, then gently press two thirds of the batter into the baking dish to form an even crust. Reserve the other third of the batter.
3. Spread the blueberry preserves over the crust then evenly sprinkle on the fresh blueberries. Crumble the reserved batter over all.
4. Bake the bars for 50 minutes, then check their progress. When the top crumb topping is evenly but lightly browned remove the bars from the oven. Let stand ten minutes then dust with the powdered sugar. These cut most easily when just slightly warm. Wipe off your knife between cuts.