Preheat oven to 350 degrees F. Place beans in a large pot and fill with water until beans are covered.
Cover pot, bring to a boil and let cook for 3 minutes, then remove from heat and drain in a colander under cold water; set aside.
Heat olive oil in a skillet over medium-high heat, and sauté onion and mushrooms for 10 minutes, stirring occasionally, or until mushrooms are brown and tender.
Sprinkle flour on top, stir and cook for 2 more minutes until flour turns golden brown.
Slowly mix in milk to avoid clumping. Add Worcestershire sauce, salt and pepper and mix until combined.
Remove from heat and mix in yogurt. Spread mixture in a 9x13-inch baking dish sprayed with nonstick cooking spray.
Mix together bread crumbs and parmesan cheese and sprinkle on top. Spray crumb topping with nonstick cooking spray.
Bake for 15 minutes. Then, turn oven to high broil and let cook for an additional 1- 2 minutes or until golden brown on top.