Place an 8-inch round metal cake pan in oven. Preheat oven to 425° (leave pan in oven).
Combine potato and onions in a large bowl. Combine salt, pepper, cream cheese, and eggs in a bowl, stirring well. Add salmon to bowl and stir to combine. Stir egg-salmon mixture into potato mixture. Remove preheated pan from oven; carefully coat pan with cooking spray. Place potato mixture in pan; pack down slightly. Bake at 425° for 50 minutes or until golden. Let stand in pan 10 minutes. Invert potato mixture onto a plate. Cut into 8 wedges; top evenly with salmon and dill.