Preheat oven to 350 degrees F.
On a sheet pan put cubed bread. Toast it in the oven until golden brown, about 5 minutes.
In a large saute pan melt the butter and saute the shallots until just wilted. Add the mushrooms and saute until browned, about 6 minutes. Remove from heat and reserve.
In a large bowl make custard, whisk together the cream with the eggs and season with the salt and pepper.
Add toasted bread cubes along with the chives, thyme and rosemary to the egg mixture. Stir in the sauteed mushrooms and mix in the grated Parmesan.
Transfer the mixture to a 9 by 13-inch baking dish, top with more grated Parmesan, to taste.
Bake for 45 minutes or until the top is golden brown and the custard is set.