Cut a hole into the center of each bread slice. Place bread on a parchment-lined baking sheet. Spread some butter on top of each slice. Carefully crack an egg into each hole. Bake at 180C for about 6 minutes - until egg whites are set and the yolks still runny. In the meantime, combine all the pesto ingredients in a food processor. Sprinkle the toasts with freshly ground pepper. Serve with cilantro pesto.