Begin by slicing the brioche or challah bread into 1-inch thick slices and arrange them in a greased 9x13-inch baking dish, overlapping slightly if necessary.
In a mixing bowl, whisk together the eggs, heavy cream, whole milk, 1 cup of sugar, vanilla extract, ground cinnamon, and salt until well combined.
Pour the custard mixture evenly over the sliced bread, ensuring all pieces are well soaked.
Cover the baking dish with plastic wrap and refrigerate for at least 8 hours or overnight to let the bread absorb the custard.
Preheat the oven to 350°F (175°C). Remove the plastic wrap and bake the French toast for 40-50 minutes, or until the custard is set and the top is golden.
Once baked, remove from the oven and let it cool slightly. Sprinkle the remaining ½ cup of sugar evenly over the top of the French toast.
To create the crème brûlée crust, carefully use a kitchen torch to caramelize the sugar until it melts and forms a crispy top. If you don’t have a torch, you can place it under the broiler for a few minutes, watching closely to avoid burning.
Allow the sugar crust to cool and harden for a few minutes. Serve warm, enjoying the contrast of the creamy custard and the crunchy topping.