01 - Melt butter with brown sugar and corn syrup in a small saucepan over medium heat, stirring constantly until smooth and bubbling. Pour mixture into the bottom of a 9x13-inch baking dish and spread evenly.
02 - Place bread slices in a single layer over the caramel, allowing slight overlap if necessary to fit the dish.
03 - Whisk together eggs, milk, cream, sugar, vanilla extract, and salt in a mixing bowl until completely smooth and well combined.
04 - Pour custard evenly over the bread. Gently press down on bread slices to help them absorb the liquid mixture.
05 - Cover dish tightly with plastic wrap and refrigerate for 8-12 hours to allow bread to fully absorb custard.
06 - Preheat oven to 350°F. Remove dish from refrigerator and let sit at room temperature while oven heats.
07 - Bake uncovered for 30-35 minutes until puffed, golden brown, and custard is completely set.
08 - Let the dish rest for 5 minutes after removing from oven.
09 - Sprinkle granulated sugar evenly over the top. Use a kitchen torch to melt and caramelize the sugar until golden and bubbly. Alternatively, place under broiler for 1-2 minutes, watching closely to prevent burning.
10 - Serve warm, spooning any extra caramel sauce from the bottom of the dish over each portion.