01 - Melt butter with brown sugar and corn syrup in a small saucepan over medium heat, stirring constantly until smooth and bubbling. Pour the mixture into a 9x13-inch baking dish and spread evenly across the bottom.
02 - Place bread slices in a single layer over the caramel, allowing slight overlap if necessary to fit all pieces.
03 - Whisk together eggs, milk, heavy cream, granulated sugar, vanilla extract, and salt in a large mixing bowl until completely smooth and combined.
04 - Pour the custard mixture evenly over the bread. Gently press down on each slice to help absorb the liquid.
05 - Cover the dish tightly with plastic wrap and refrigerate for 8 to 12 hours to allow the bread to fully absorb the custard.
06 - Preheat oven to 350°F. Remove the dish from the refrigerator and let it sit at room temperature while the oven heats.
07 - Bake uncovered for 30 to 35 minutes until puffed, golden brown, and the custard is completely set.
08 - Remove from the oven and let cool for 5 minutes before proceeding.
09 - Sprinkle granulated sugar evenly over the top. Use a kitchen torch to melt and caramelize the sugar until golden and crispy. 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.