Tear off heavy-duty aluminum foil sheets to create your packets and grease the shiny side generously with butter.
In a large bowl, whisk together the eggs, milk, vanilla extract, and ground cinnamon until well combined.
Add the 6 cups of cubed bread to the bowl and gently toss until the liquid is absorbed, then carefully fold in the 1 cup of fresh raspberries.
Divide the bread and berry mixture evenly onto the greased foil sheets, fold the foil over the mixture, and crimp the edges tightly to seal the packets.
Place the packets over a medium-hot campfire or grill for 15 to 20 minutes, turning once, until the bread is toasted and the custard is fully set.
Carefully open the packets, dust with powdered sugar, and serve warm.