Rinse spinach well; drain.
Melt butter in a large skillet over medium heat. Add spinach, and cook just until wilted.
Combine flour, salt, pepper, and garlic powder in large bowl. Add spinach, eggs, whipping cream, and Parmesan cheese, stirring well. Pour mixture into a lightly greased 9-inch pie plate.
Bake at 350° for 25 minutes or until pie is set. Let stand 10 minutes. Cut pie into wedges.