Layer half of the bread slices in a greased baking dish.
Top with ham, turkey, and shredded Swiss cheese.
Layer the remaining bread slices on top.
In a mixing bowl, whisk together the beaten eggs, milk, mustard, and mayonnaise.
Pour the egg mixture evenly over the bread layers.
Bake in the preheated oven for 45 minutes or until golden brown and set.
While the casserole is baking, prepare the raspberry sauce by combining raspberry jam, water, and lemon juice in a small saucepan. Heat over medium heat until smooth and warm.
Serve the casserole hot with raspberry sauce drizzled on top or on the side.
Notes:
For a twist, try using different types of bread or cheese.