Coat a medium casserole dish with cooking spray and set aside. Heat oven to 350. Steam vegetables until crisp tender and rinse under cold water to stop the cooking process. Cut vegetables into bite size pieces. Set aside. In a large frying pan melt the butter over medium heat. Add the onion and cook until tender. Stir in flour, salt, garlic powder and pepper. Slowly add milk, whisking constantly. Cook while whisking until mixture becomes thickened and bubbly. Add cream cheese and stir until just melted. Pour over vegetables and toss well to coat evenly. Pour mixture into prepared casserole dish. Combine bread crumbs, parmesan cheese and 2 tablespoons melted butter. Sprinkle on top of casserole and place in the oven. bake for 25 to 30 minutes or until topping is nicely browned and mixture is bubbly.