Preheat your broiler to high to make the caramelized sugar topping. Evenly distribute the powdered sugar onto a tiny parchment paper-lined baking sheet. Broil the sugar for two to three minutes, or until it melts and becomes golden brown. Keep a cautious eye to prevent burning. Remove from the oven and allow it to cool fully after caramelizing.

Combine the ingredients for the custard in a big bowl and whisk the eggs, heavy cream, milk, sugar, cinnamon, vanilla essence, and salt until thoroughly mixed.

Prepare the bread: Put the bread pieces in a 9 x 13-inch baking dish in a single layer. Evenly drizzle the bread with the melted butter.

Drizzle the bread with the custard: Slowly drizzle the bread with the prepared custard mixture, making sure that each piece is saturated equally. Place plastic wrap over the dish and place it in the refrigerator for at least two hours, or better yet, overnight.

Bake the dish after preheating the oven: Set the oven temperature to 350°F (175°C). After taking the casserole out of the fridge, allow it to come to room temperature for fifteen minutes. Bake the casserole uncovered for 35 to 40 minutes, or until the top is puffy and browned.

Cool and caramelize the sugar topping: After baking, take the casserole out of the oven and set it aside to cool for approximately half an hour on a wire rack. The dish may crumble if you cut it before it's heated.

Evenly cover the dish with the cooled caramelized sugar topping before serving. Gently caramelize the sugar with a cooking flame until it turns golden brown and frothy. As an alternative, heat your broiler too high and monitor the dish very carefully for one to two minutes to make sure the sugar doesn't burn.