In a non-stick skillet melt butter over medium heat.
Add scallions and cook, stirring, until soft.
In a bowl whisk together eggs and milk and season with salt and pepper. Reduce heat to medium low and add egg mixture to skillet. Cook, stirring, until almost set.
Transfer eggs to bread cups and top with salmon and caviar.
Preheat oven to 300 degrees F.
Using a 2 2/3 round cutter (or juice glass) cut bread into rounds. Butter both sides with melted butter and press into mini muffin tins, being careful not to tear bread. Season with salt.
Bake for 10 to15 minutes until toast are firm to the touch and slightly golden in color. Fill with desired fillings.