1Spray 13x9-inch (3-quart) baking dish with cooking spray.
2Sprinkle 1 box potatoes in baking dish. Place half of the cream cheese cubes and the salmon pieces over potatoes. Sprinkle with dried onion. Top with remaining box of potatoes and cream cheese.
3In large bowl, beat Bisquick mix, pepper, milk and eggs with whisk or fork until blended. Pour over mixture in baking dish. Sprinkle with shredded cheese. Cover with foil; refrigerate at least 4 hours but no longer than 24 hours.
4Heat oven to 375°F. Bake uncovered 32 to 38 minutes or until golden brown and knife inserted in center comes out clean. Sprinkle with green onions. Let stand 10 minutes before serving.