Heat oven to 400Â°.
Cook spinach as directed on package; drain.
Stir in onion and lemon juice.
Spread spinach in ungreased baking dish, 8x8x2 inches.
Sprinkle with cheese; top with egg slices.
Melt 3 tablespoons butter in saucepan over low heat.
Blend in flour and seasonings.
Cook over low heat, stirring until mixture is smooth and bubbly.
Remove from heat.
Stir in milk.
Heat to boiling, stirring constantly.
Boil and stir 1 minute.
Pour over eggs.
Toss bread crumbs in melted butter; sprinkle over sauce.
Bake uncovered 20 minutes.