Break the four eggs into a bowl. Add half the salt and half the pepper and whisk well.
Warm a frying pan over medium-high heat. Add half the butter to the frying pan and then add in the mushrooms. Add the other half of the salt and pepper. Stir and let cook for about five minutes or until the mushrooms begin to brown. Stir periodically. Basically, you want to soften and evaporate most of the water from the mushrooms while giving the edges some color. When finished, remove the pan from the heat.
When finished, add the chives or scallions to the mushrooms and mix everything together.
Warm another frying pan over medium-low heat. Add the remaining butter to the pan and then add the whisked eggs. Swirl the eggs around the pan so they cover the bottom and then let cook. When cooked through, you can either flip the omelette or leave as is. Just make sure it's cooked all the way through. Remove the pan from the heat.
Pour the contents of the mushroom pan onto half of the eggs. Then, flip the omelette over them so you're left with a half circle. Cut the omelette in half.
Toast the ciabatta and place half of the omelette on each roll.
Serve and enjoy!