In a 10-inch skillet, cook beef and onion over medium heat 8-10 minutes, stirring occasionally, until beef is brown; drain.
Stir in salt. Spread in pie plate. Sprinkle with cheese.
In a small bowl, stir remaining ingredients with fork or wire whisk until blended. Pour into pie plate.
Bake about 25 minutes or until knife inserted in center comes out clean.