Philly Cheesesteak Casserole

Philly Cheesesteak Casserole
1 (16 ounce) package bowtie pasta
2 tablespoons vegetable oil
2 onions chopped
1 1/2 pounds ground beef
1 (10 ounce) can cream of mushroom soup
1 soup can milk
4 (4 ounce) cans mushrooms
1/2 teaspoon thyme
4 cups shredded Cheddar cheese, divided
Salt and pepper to taste
1 cup bread crumbs
3 tablespoons butter, melted
Heat oven to 375 degrees F. Bring a large pot of lightly salted water to a boil. Add pasta and cook according to package directions. Drain and set aside. Heat vegetable oil in a skillet over medium heat. Sauté onions until they begin to soften. Add ground beef and cook, stirring until evenly browned. Drain off grease and pour into the bowl with the pasta. Stir in the soup, soup can of milk, mushrooms and thyme until well blended. Mix in 3 cups of the cheese, and season with salt and pepper. Pour the mixture into a greased 9 x 13-inch baking dish. In a small bowl, mix together the bread crumbs and melted butter. Mix in remaining cheese. Sprinkle the mixture evenly over the top of the baking dish. Bake 30-35 minutes or until top if golden and crispy.