• Preheat oven to 350 and have a rack in the middle. Line a 13x9 baking dish with foil and butter or spray with baking spray.

To make the jam

• Place all ingredients in a saucepan and cook over medium/high heat, stirring every once in a while. Cook about 10-15 minutes. The blueberries will release their juices and the peaches will break down. The entire mixture should be thick and reduced when totally finished.
• Set this aside to cool off.

To make the shortbread bars

• Combine the butter, sugar, and flour for the crust in a large bowl or the bowl of your stand mixer. Using the paddle attachment, or a spatula, mix until well-combined and the mixture comes together. Take out ⅓ cup  shortbread and set aside to crumble on top of the bars. Press the rest of the crust into the bottom of the prepared pan. Bake for 20 minutes. Cool on a cooling rack for about a 20 minutes.
• Pour and spread the cooled compote over the slightly cooled crust. Crumble the remaining ⅓ cup of the shortbread over the top of the filling. Continue baking for 45 minutes until set and slightly golden on top.
• Cool the bars completely before cutting and serving.