Grease a 25 cm spring-form pan with a little mayonaise. Mash eggs, mayonaise (just enough to hold eggs together), salt, and pepper together. Spread into bottom of pan. Spread scallions on top of egg salad. Mix cream cheese and sour cream until smooth. Spread over scallions. Recipe can be prepared up to this point the day before (recommended). Place the spring-form on a paper towel on a plate (the sour cream tends to separate). Spread the caviar into an aesthetic design use wax paper for masking and toothpicks to move caviar. Serve with plain crackers such as Carr's Table Water Biscuits.