Prepare a 9 by 13 inch baking dish by spraying it with cooking spray.
In a large bowl, combine the eggs, whole milk, heavy cream, whole milk, vanilla extract, and granulated sugar.
Add the cubed French bread, and stir to coat all the bread. Then gently stir in the frozen berries.
Pour the mixture into the pan, cover with foil and refrigerate for at least one hour or up to 24 hours.
When you are ready to bake it, remove it from the refrigerator and preheat your oven to 350 degrees.
Combine the brown sugar, butter, and quick oats together in a bowl using the back of a fork. Sprinkle over the french toast.
Bake for 50 minutes or until the edges begin to pull away from the pan. There will be excess liquid there but you should still be able to see the bake pulling away at the end. Let stand for 10 minutes before serving (a perfect time to make your whipped cream).
When you put the bake into the oven, put a large metal mixing bowl (or the bowl for your stand mixer) into the freezer as well as the whisk attachment(s) for your stand mixer or hand held mixer. Leave them in the freezer for at least 20 minutes or the entire time the french toast is in the oven.
After removing the bake from the oven, take the bowl and whisk attachment from the freezer. Add the 2 TBSPs of sugar, and then add in 1 cup of heavy cream. Mix until peaks begin to form.
Serve over the french toast and enjoy!
You should be able to gently push a finger into the butter but not go all the way through it.