In a skillet, melt 1 tablespoon of butter over medium heat.
Add the sliced Spanish onion to the skillet and cook until they are delicately browned, stirring occasionally.
Once the onions are browned, stir in the chopped parsley, salt, and pepper.
In another saucepan, melt the remaining 1 tablespoon of butter over medium heat.
Stir in the flour to create a roux and cook for 1-2 minutes until lightly golden.
Gradually pour in the hot milk, stirring constantly to avoid lumps.
Cook the sauce until it thickens to a creamy consistency.
Add the quartered hard-boiled eggs to the sauce and gently stir to coat them with the sauce.
Cook for another minute until the eggs are heated through.
Place the toasted bread slices on serving plates.
Spoon the savory eggs and sauce over the toast slices.
Serve your delicious Spanish Onion and Parsley Eggs on Toast hot and enjoy!