Heat 1/3 cup butter in a large skillet; add mushrooms and onion.
Cook over medium heat 5 minutes, stirring occasionally.
Using a slotted spoon, remove mushrooms; set aside.
Add 2 tablespoons butter to skillet; blend in flour and cook until bubbly.
Remove from heat and gradually add cream, stirring constantly.
Continue to stir and bring mixture to boiling; cook 1 to 2 minutes.
Add 1 cup of the sauce to a mixture of the mushrooms, pepper, oregano, ham, and olives.
Toss lightly until well mixed.
Lightly butter a shallow baking dish.
Spoon enough cream sauce over bottom of baking dish to make a thin layer.
Spoon 2 to 3 tablespoons of the filling onto the center of each crepe.
Fold one edge of crepe over filling and roll up.
Place filled crepes in baking dish with open edges down.
Spoon remaining sauce over crepes; sprinkle with Parmesan cheese.
Heat, covered, in a 350CF oven for 15 minutes.
Remove the dish from oven and uncover.
Place baking dish under broiler with top of crepes 3 to 4 inches from source of heat.
Broil 3 to 4 minutes, or until cheese is lightly browned.