Cut the ciabatta into four pieces (two sandwiches) and toast to your liking.
Bring a skillet to medium heat. Add the olive oil, then the mushrooms. Make sure not to crowd the pan. Season the mushrooms and cook on medium heat, making sure you can hear a low sizzle at all times. Stir occasionally, but not too much, allowing the mushrooms to brown and crispy up evenly. Cook for about 5-7 minutes or until the mushrooms are crisp on the edges.
In a small blender or food processor, blend together the basil oil until it is a light opaque green. Make sure the ingredients emulsify into a smooth sauce.
Toss the dressing over the microgreens.
Assemble the sandwich with a thin layer of basil dressing on the bread, then add the mushrooms and the salad. Grate fresh parmesan on top (not mandatory but it really changes EVERYTHING).
Serve whenever!