How to Make It
Grease a round waffle iron with butter; preheat to high. Whisk together flour, sugar, salt, and baking powder in a bowl. Whisk together buttermilk, egg, and melted butter in a small bowl until well combined. Add buttermilk mixture to flour mixture; whisk just until incorporated.
Pour half of waffle batter (about 1/2 cup) onto preheated waffle iron; spread gently over iron grid with a small spatula. Close iron; cook until browned and slightly crisp, about 3 minutes. Transfer to a wire rack; cool slightly, about 5 minutes. Repeat with remaining batter.
Following the waffle grid marks as a guide, cut each waffle into 4 wedges, then cut 3 long rectangular pieces from each wedge to yield 12 pieces per waffle. (Discard scraps, or reserve for another use.)
Spoon crème fraîche into a small ziplock plastic bag; snip the tip off one corner of bag to form a 1/4-inch opening. Spoon caviar evenly into outermost square of each rectangular waffle piece; pipe a small dollop of crème fraîche into squares directly next to caviar. Garnish with chives. Transfer to a platter and serve.