In a well-buttered baking dish, toss the cubed French bread.
Sprinkle the mixed berries evenly over the bread.
In a mixing bowl, whisk together eggs, milk, heavy cream, granulated sugar, vanilla extract, cinnamon, nutmeg, and a pinch of salt.
Pour this mixture evenly over the bread and berries. Gently press down with a spatula to ensure the bread soaks up the egg mixture.
Let the dish rest for about 20 minutes to absorb the flavors, or refrigerate overnight for a deeper infusion.
Preheat your oven to 350°F (175°C).
Mix brown sugar and melted butter. Drizzle this over the top for a crisp, caramelized finish.
Place the dish in the oven and bake for 45 minutes, or until the top is golden and the center is set.
Allow to cool slightly. Serve warm, with a drizzle of maple syrup, a dollop of whipped cream, or a dusting of powdered sugar, if desired.