Heat oven to 400°F. Lightly spray 9-inch glass pie plate with cooking spray. In 10-inch skillet, heat oil over medium-high heat. Cook ham in oil 5 minutes, stirring occasionally, until browned. Stir in greens and onion. Cook 5 minutes longer until onion is tender and liquid is evaporated. Spoon half of the mixture into pie plate. Sprinkle with 3/4 cup of the cheese. Repeat layers.