01 - In a small saucepan, melt the butter with brown sugar and corn syrup over medium heat, stirring constantly until smooth and bubbling. Pour the mixture into the bottom of a 9x13-inch baking dish and spread evenly across the surface.
02 - Place the bread slices in a single layer over the caramel, arranging them so they slightly overlap if necessary to fit the dish.
03 - In a large mixing bowl, whisk together the eggs, milk, heavy cream, granulated sugar, vanilla extract, and salt until completely smooth and well combined.
04 - Pour the custard mixture evenly over the arranged bread slices. Gently press down on each piece of bread to help it absorb the liquid custard.
05 - Cover the dish tightly with plastic wrap and refrigerate for 8 to 12 hours to allow the bread to fully soak up the custard mixture.
06 - Preheat your oven to 350°F. Remove the dish from the refrigerator and let it sit at room temperature while the oven heats up.
07 - Bake uncovered for 30 to 35 minutes until the French toast is puffed and golden brown, and the custard is completely set.
08 - Remove the dish from the oven and allow it to cool for 5 minutes before proceeding to the caramelized topping.
09 - Sprinkle the granulated sugar evenly over the entire surface. Use a kitchen torch to melt and caramelize the sugar until it forms a crispy golden crust. Alternatively, place under the broiler for 1 to 2 minutes, watching closely to prevent burning.
10 - Serve warm, spooning any extra caramel sauce from the bottom of the dish over each portion.