01 - Preheat oven to 375°F. Lightly grease a medium baking dish with butter or oil.
02 - Steam or blanch fresh vegetables for 3 to 4 minutes until just tender, then drain well. For frozen vegetables, thaw completely and pat dry to remove excess moisture.
03 - In a large mixing bowl, combine the prepared vegetables, low-fat cream of mushroom soup, milk, shredded cheese, dried thyme, garlic powder, salt, and black pepper. Mix thoroughly so all pieces are evenly coated.
04 - Transfer the vegetable mixture to the prepared baking dish and spread evenly using a spoon or spatula.
05 - In a small bowl, mix breadcrumbs with melted butter until well combined. Sprinkle the breadcrumb mixture evenly on top of the casserole.
06 - Bake uncovered for 25 to 30 minutes, or until the topping is golden brown and the filling is bubbling around the edges.
07 - Allow the baked casserole to rest for 5 minutes before serving warm.