Serve warm brie in its baking dish. Put the dish on a wooden board or a plate. Surround it with dippers. Give everyone a small knife or spoon. Let them go to town. It’s a communal, messy, joyful experience. Napkins are mandatory.
Don’t try to slice the warm brie. It will just ooze all over the place. Instead, let people scoop it up like a dip. That’s the whole point. Embrace the ooze.