In large bowl, whisk eggs, heavy cream, milk, Gruyere cheese, maple syrup and cinnamon. Add chopped bacon, saving 2 tablespoons for later. Pour over bread in baking dish. With hands, press down on bread to submerge.
Cover baking dish with plastic wrap. Refrigerate at least 5 hours, or overnight.
Heat oven to 375 F. Remove plastic. Sprinkle remaining bacon and Swiss cheese over top of bread mixture.
Bake 45-50 minutes, or until golden brown and set.
Top with blackberries and dust with powdered sugar before serving.
