The night before, grease a large casserole dish. Check that you can lay out 6 slices of bread evenly across the bottom of your casserole dish. If they do not fit, trim the bread as needed so you can fit the stuffed french toast sandwiches evenly. I use this 13-inch x 10-inch casserole dish.
In a small bowl, mix together the cream cheese and raspberry jam.
Spread on a thick layer of the cream cheese mixture on a slice of bread and close it with a second slice to make a sandwich. Place it in the casserole dish. Repeat with the remaining slices. You will want to divide up all of the cream cheese mixture evenly.
Whisk the eggs together. Whisk in the milk, vanilla and salt.
Gently pour the mixture over the French toast sandwiches. Allow it to soak for 1 minute. Then carefully using the help of a spatula, flip each sandwich over. Don't let it soak too long because if the bottom bread becomes too soggy, it's hard to flip.
Cover and set in the refrigerator to soak overnight.
In the morning, take the french toast casserole out of the oven 30 minutes before baking. Preheat the the oven to 350°F / 175°C.
Bake in the middle of the oven for about 55 minutes. The Baked Stuffed French Toast Casserole is done when there's no more liquid left and the egg is set.
Remove from the oven and allow to cool for 5 minutes before serving.
Serve warm, topped with maple syrup, whipped cream and more jam.