Preheat your oven to 350°F (175°C) and grease a 9×13-inch baking dish.
Spread the cubed bread evenly in the dish and sprinkle the wild berries over the top.
In a large mixing bowl, whisk together the eggs, milk, sugar, vanilla, cinnamon, and salt until well combined. Add the melted butter and mix until smooth.
Pour the custard mixture over the bread and berries, pressing down gently with a spatula to ensure all bread gets soaked. Let it sit for about 15 minutes.
Bake for 35-40 minutes, or until the custard is set and the top is golden brown.
Allow to cool for about 10 minutes, dust with powdered sugar if desired, and drizzle with cream or sweet sauce.
