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 all pieces.
03 - Whisk together eggs, milk, cream, sugar, vanilla extract, and salt in a large mixing bowl until completely smooth and combined.
04 - Pour custard mixture evenly over the arranged bread slices. Gently press down on bread to help absorb the liquid.
05 - Cover dish tightly with plastic wrap and refrigerate for 8 to 12 hours to allow bread to fully soak up 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 to 35 minutes until puffed, golden brown, and custard is completely set.
08 - Remove from oven and let cool for 5 minutes before finishing.
09 - Sprinkle granulated sugar evenly over the surface. Use kitchen torch to melt and caramelize sugar until golden and crispy, or broil for 1 to 2 minutes watching closely to prevent burning.
10 - Serve warm, spooning any remaining caramel sauce from the bottom of the dish over each portion.