How to Make It
Heat a large nonstick skillet. Generously butter both sides of the bread slices. Add 2 slices of bread to the skillet and toast over moderately high heat, turning once, until golden and crisp on the edges, about 3 minutes total. Transfer to plates. Repeat with the remaining bread.
Wipe out the skillet and melt the 4 tablespoons of butter in it. In a large bowl, beat the eggs with a generous pinch each of salt and pepper, then stir in the 2 tablespoons of chives. Add the eggs to the skillet and cook over moderately low heat, stirring constantly, until small curds form and the eggs are creamy, about 7 minutes. Remove the skillet from the heat and season the eggs with salt and pepper.
To serve, spoon the eggs onto the toasts and generously top with finely grated bottarga and finely chopped chives.