In a large mixing bowl, whisk together the eggs, whole milk, heavy cream, granulated sugar, vanilla extract, ground cinnamon, and salt until well combined.
Add the cubed French bread to the egg mixture, gently folding to ensure all pieces are coated. Cover the bowl with plastic wrap and refrigerate for at least 2 hours, or overnight for best results.
Preheat your oven to 350°F (175°C).
Grease a 9x13-inch baking dish with non-stick spray or butter. Pour the soaked bread mixture into the prepared dish, spreading it evenly.
In a small bowl, mix together the brown sugar and melted butter. Drizzle this mixture over the top of the bread.
Bake in the preheated oven for 45-50 minutes, or until the top is golden brown and the center is set.
Remove from the oven and let it cool for about 10 minutes before serving. Sprinkle the granulated sugar evenly over the top and use a kitchen torch to caramelize the sugar until golden and crispy.