1. Coarsely grate the Provolone cheese. Wipe and thinly slice the mushrooms. Dice the bread. Melt the Provolone in an earthenware fondue pot over a very low heat. Cut up and add the Gorgonzola.
2. Beat the milk with the eggs and gradually stir into the warm cheese mixture. Do not allow the fondue to become too hot, as at over 60°c (140°f) the eggs will curdle. Flake the butter and stir a little at a time into the fondue with the pepper, mushrooms and wine.
3. Place the fondue on the dining table over a spirit lamp. Spear the bread on fondue forks and stir in the cheese until well covered.