In a small saucepan cook the butter over moderate heat, swirling the pan occasionally, until it is golden brown, being careful not to let it burn, and keep it warm.

Spread each pancake with about 1 tablespoon of the sour cream, or to taste, top the sour cream with about 1 teaspoon of the caviar, or to taste, and sprinkle each pancake with some of the egg yolk and scallion. Stack 3 pancakes on each of 2 plates and drizzle each stack with some of the brown butter.