the fruit has broken down, 5 to 6 minutes. in a small bowl, mix about 3 tablespoons of the fruit mixture with the cornstarch until smooth. add the cornstarch mixture to the fruit and simmer for another 2 to 3 minutes. remove the jam from the heat and let cool slightly.
top the bottom crust with the fruit and spread it out evenly. top the fruit with the oat crumb mixture, squeezing it to make some larger clumps. bake until the top is golden brown, 28 to 32 minutes. transfer the pan to a rack to cool completely. using the parchment, lift out the entire bar mixture and place it on 