The night before you want to serve this French toast:
Butter a 9x13 baking dish.
Whisk together the eggs, half-and-half, sugar, vanilla, bourbon, and salt in a large bowl. Make sure the eggs are well incorporated into the mixture.
Dip each slice of challah bread into the egg mixture. Let the excess liquid drain off and lay it into the casserole dish at a slightly up-right angle. You are not trying to lay them flat in the dish, they should overlap up against each other slightly.
Keep adding slices to the dish until the bottom is completely covered with bread. You may have to readjust some of the slices to make sure there aren't any big holes in the casserole. Pour the remaining egg mixture evenly over the top of the bread slices. Cover the dish with plastic wrap and let it chill in the fridge overnight.
The morning you want to serve your French toast bake:
Preheat the oven to 350°F with an oven rack positioned in the center of the oven. Set the casserole on the counter while you prepare the praline topping.
In a small saucepan, melt the butter over medium heat. Add the brown sugar, corn syrup, and bourbon and whisk them in until smooth. Bring the mixture to a slight simmer. When the praline starts to bubble, add the pecans and stir them in to heat through for 30 seconds. Spoon the topping evenly over the casserole and then cover with aluminum foil.
Bake the French toast for 25 minutes. Uncover the dish and continue to bake for an additional 20 minutes or until the casserole is slightly bubbling and the top is golden brown. Be careful that the pecans don't burn, it can happen quickly at the end.
Let the French toast bake cool for 10 minutes before serving. This will help the praline to firm up a little and prevent hot boiling sugar burns when you gobble it up.