Prepare the bread: Cut a 3-inch slit in the middle of each slice of french bread to create a pocket.
Stuff: Insert one slice of cheese and once slice of Canadian bacon into each bread pocket, folding if necessary.
Arrange: Place the stuffed slices into a greased 9x13-inch baking dish.
Make the custard: In a medium bowl, whisk together the milk, melted butter, eggs and vanilla. Pour evenly over bread slices.
Chill overnight: Cover dish and refrigerate for at least 4 hours, or overnight, allowing the bread to soak up all of the custard mixture.
Bake: Preheat the oven to 425 degrees. Uncover and bake for 30 minutes, or until golden brown. For extra crispy french toast, bake for 15-20 minutes, flip each slice, and bake another 10-15 minutes or until golden brown.
Serve: Dust with powdered sugar, top with fresh berries, and drizzle with syrup. Serve warm.