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 the bottom of a 9x13-inch baking dish and spread evenly across the surface.
02 - Place bread slices in a single layer over the caramel, allowing slight overlap if necessary to fit all pieces snugly in 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 the custard evenly over the arranged bread. Gently press down on each slice to help absorb the liquid mixture.
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 the French toast is puffed, golden brown, and the custard is completely set.
08 - Remove from oven and let rest for 5 minutes before proceeding with the topping.
09 - Sprinkle granulated sugar evenly over the top. Using a kitchen torch, melt and caramelize the sugar until golden and crisp. Alternatively, place under the broiler 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.