Heat oven to 400ºF. Grease 9-inch pie plate. Sprinkle asparagus, onions, 3/4 cup of the cheese and the salmon in pie plate.
Stir remaining ingredients until blended. Pour into pie plate.
Bake 30 to 35 minutes or until knife inserted in center comes out clean. Sprinkle with remaining cheese. Bake about 2 minutes longer or until cheese is melted. Cool 5 minutes.