Heat oil and butter in heavy-bottomed pot. Wilt onions, celery, bell pepper, and garlic.
Add ground beef, salt and pepper, green onions, and parsley. Cook until browned.
Put meat in frozen crust. Arrange cheese over meat filling.
Flip over other frozen pie crust. Let thaw 10-20 minutes. Crimp edges and cut 3 2-inch slits in pie crust. Put pie on baking sheet.
Bake at 350 degrees for 30 minutes.