Spray a 8-inch baking pan with non-stick spray. Line pan with a sheet of parchment paper Leave an overhang and spray the paper for easy removal.
In a large bowl, whisk together the rolled oats, flour, brown sugar, cinnamon and salt.
Pour in the melted butter and mix until everything is combined and chunky. Set aside 1/2 cup of this mixture.
Pour the remaining mixture into the bottom of the prepared pan and pack down the crust.
Layer ½ of the strawberry and blueberry mixture over the crust
Sprinkle the cornstarch over the fruit then squeeze half of a lemon over the fruit, Next sprinkle half of the granulated sugar over it and then top with the remaining fruit.
Then sprinkle the remaining granulated sugar on top.
Spread the ½ cup mixture of granola on top.
Bake for 40 to 45 minutes, until the granola is starting to turn golden and the fruit is bubbling.
Set out to cool completely before cutting
Once cooled, mix 2 tbsp of the heavy cream in with the powdered sugar. Slowly add more cream until the desired consistency has been reached. Drizzle all over the bars.
Store leftovers in the refrigerator. These can be frozen.
Notes
If you choose to cut the bars while warm it will be more like a cobbler. I usually let them cool for about an hour and then refrigerate for a few hours to get a clean cut.