In a 10-inch, ovenproof, nonstick skillet, heat the oil over medium heat. Add the arugula and garlic. Cook, stirring frequently until the arugula has wilted, about 1 minute. Pour the egg mixture into the pan and stir to combine the ingredients. Cook, without stirring for 4 minutes. Transfer the skillet to the oven and bake until set, about 10 to 12 minutes.