In a large mixing bowl, whisk together the eggs, milk, heavy cream, granulated sugar, vanilla extract, cinnamon, and salt until well combined.
Arrange the brioche slices in a greased baking dish, slightly overlapping them if necessary.
Pour the egg mixture over the brioche, ensuring that all slices are well soaked. Cover with plastic wrap and refrigerate for at least 2 hours or overnight for best results.
Preheat your oven to 350°F (175°C).
Remove the plastic wrap from the dish. Sprinkle the brown sugar evenly over the soaked bread.
Bake in the preheated oven for 30-35 minutes, or until the top is golden and the center is set.
For an extra special touch, use a kitchen torch to caramelize the brown sugar topping until bubbly and golden.
Allow it to cool for a few minutes before slicing.
Serve warm with fresh berries on top and a dollop of whipped cream if desired.