01 - Preheat oven to 350°F. Grease a 9x13-inch baking dish with butter.
02 - In a large mixing bowl, whisk together eggs, milk, Dijon mustard, salt, and pepper until well combined.
03 - Layer half of the bread cubes evenly in the baking dish. Sprinkle half of the ham, turkey, and Swiss cheese over the bread. Dot with half of the cream cheese cubes.
04 - Drizzle half of the raspberry preserves over the layer. Repeat with remaining bread, meats, Swiss cheese, cream cheese, and raspberry preserves.
05 - Pour the egg mixture evenly over the casserole, pressing gently to soak the bread.
06 - Cover with foil and refrigerate for at least 1 hour, or overnight for best flavor.
07 - Remove from refrigerator while oven preheats. Bake covered for 30 minutes, then uncover and bake for an additional 15 minutes or until golden and set.
08 - Cool for 10 minutes. Dust with powdered sugar and serve warm, with extra raspberry preserves on the side.