Gently wash the mushrooms under cold water and pat dry.
Dice the mushrooms and sauté them in a little oil with salt and pepper.Break the eggs into a bowl and whisk them. Add the flour, melted butter, grated cheese, and mushrooms. Season with salt and pepper to taste, and add the nutmeg.
Generously grease a loaf pan with butter and pour in the batter. Bake for 45 minutes (or until a knife inserted into the middle comes out clean).