Pre-heat oven to 350 degrees.
In a small sauce pan, melt the butter.
Combine the melted butter, maple syrup (or brown sugar), vanilla, and optional pecans. Pour this mixture into the bottom of a 9×13 baking dish.
In a separate large bowl, whisk together the eggs, heavy cream, and milk until smooth.
Cube the bread.
Place the cubed bread into the custard bowl and toss gently to ensure every piece soaks up the custard.
Spread the soaked bread evenly over the maple-butter layer in the dish.
Cover and refrigerate for 8 hours or bake uncovered right away if all the custard is soaked into the bread before pouring over the maple butter layer.
Bake uncovered at 350°F for 45 minutes, or until the top is slightly crispy and the center no longer jiggles.
Spoon each serving and flip it upside down so the caramelized maple-butter layer becomes the topping. Serve with optional berries & powdered sugar.