Heat oven to 400°F. Spray 9-inch glass pie plate with cooking spray.
In 10-inch skillet, cook beef and onion over medium heat 8 to 10 minutes, stirring occasionally, until beef is brown; drain. Stir in salt. Spread in pie plate. Sprinkle with cheese.
In medium bowl, stir remaining ingredients with fork or wire whisk until blended. Pour into pie plate.
Bake 29 to 33 minutes or until knife inserted in center comes out clean. Let stand 10 minutes before serving.
