Preheat the oven to 350 degrees F and line an 8x8 square inch baking dish with parchment paper.
In a medium bowl add the sliced peaches. Add the vanilla extract, cornstarch and the raspberry peach preserves and gently mix to combine. Set aside.
In a food processor add the flour, ¾ cup brown sugar, butter, cinnamon, 1 tablespoon milk and salt. Pulse until the mixture is crumbly. Press ½ of the crumbly mixture into the bottom of the prepared baking dish, pressing the dough into the pan to form the bottom crust. To the remaining dough add an additional ¼ cup brown sugar and stir to combine. This will be the crumbly streusel topping.
Spoon the peach mixture over the crust and arrange the fresh raspberries over the top. Sprinkle the remaining crumbly streusel dough evenly over the top of the fruit and bake for 45-50 minutes, or until the top is lightly golden.
Allow to cool completely before cutting into bars. Serve with fresh whipped cream or vanilla ice cream if desired. ENJOY!