Salmon Shortcake

1 can salmon, de-boned
1 (8-count) can biscuits
3 tablespoons chopped onions
4 tablespoons butter
4 tablespoons flour
2 cups milk
1 cup shredded cheese

Saut onions in butter. Blend in flour. Add milk slowly and cook until sauce is thick gravy. Add cheese; let melt. Add drained and de-boned salmon. Pour into greased casserole. Top with biscuits. Bake at 425 degrees F for 7 minutes, then turn biscuits over. Bake another 7 to 10 minutes.