Keep in mind this egg-to-person rule: every egg you use represents a single serving. So, if you are having a soufflé party for 6, use 6 eggs. Simple.
Slice whatever mushrooms you are using – in this case bear's head mushrooms from Far West Fungi were my fungus of choice - toss them into a hot skillet and sauté them until water bubbles out and they brown slightly.
Separate your eggs and stir the mushrooms into the yolks. Whip your egg whites until they form stiff peaks, and fold the mushroom-yolk into the egg whites 1/3 at a time. Butter your soufflé ramekins, and fill them three-quarters of the way up. Put them in the oven - in a baking dish with water coming halfway up the ramekin. Bake for roughly 20 minutes, or until the tops are nicely browned.