4 tbsp Danish unsalted butter, softened, plus more for serving
2 cups mixed berries (such as blueberries, raspberries and blackberries)
¼ cup sliced almonds
maple syrup, for serving
Butter a 9×13-inch pan and fill with bread cubes. Set aside.
In a large bowl, whisk together eggs, milk, granulated sugar, brown sugar, vanilla, cinnamon and salt. Pour over bread cubes and gently press down a few times to help soak the bread. Cover with plastic wrap and let sit 1 hour at room temperature or overnight in the refrigerator.
Preheat oven to 375°F.
Bake French toast casserole, covered with foil, for 30 minutes.
Meanwhile, make streusel topping. Whisk together flour, brown sugar, cinnamon and salt in a medium bowl. Blend in butter with your fingers until well combined. Refrigerate until ready to use.
Remove French toast from oven and top with fresh berries. Crumble streusel over top and sprinkle with almonds. Bake, uncovered, another 20-25 minutes, or until center is cooked through and berries are soft.