Begin by melting the butter in a small saucepan over medium heat. Once melted, add the brown sugar and corn syrup, stirring until the sugar dissolves completely. Pour this mixture into a 9x13-inch baking dish.

Remove the crusts from the slices of bread and arrange them in a single layer within the prepared baking dish. In a separate bowl, whisk together the eggs, half-and-half cream, vanilla extract, orange liqueur, and salt. Pour the custard mixture evenly over the bread. Cover the dish and refrigerate it for at least 8 hours, or overnight.

The following day, preheat your oven to 350°F (175°C). Before baking, bring the dish to room temperature.

Bake the casserole, uncovered, in the preheated oven for 35 to 40 minutes, or until the top is lightly browned and puffed up.