Preheat oven to 350°F.
Bring a large skillet of salted water to a boil. Cook asparagus in boiling water until just tender.
Drain and plunge in ice water to stop cooking immediately. When cool, cut asparagus into 1/2-inch pieces and set aside.
Melt butter in an ovenproof skillet over medium heat. Meanwhile, beat eggs and blend with cheese, asparagus and salt.
When butter is melted, reduce heat to medium-low and add eggs to skillet.
Cook until bottom is set, about 5-7 minutes.
Transfer skillet to oven and bake until top is set. Or broil for a brown top.
Serve warm or at room temperature.