Preheat broiler. Add olive oil to a heavy broiler proof 10-inch-diameter nonstick skillet over medium heat. Add leeks and sauté 4 minutes. Add asparagus and shiitake mushrooms, sprinkle lightly with salt, and sauté until tender, about 6 minutes. Whisk eggs, 3/4 cup Fontina cheese, 1/2 teaspoon salt, and 1/2 teaspoon pepper in a medium bowl. Add egg mixture to skillet; fold gently to combine. Cook until almost set. Sprinkle remaining 1/4 cup Fontina cheese and Parmesan cheese over. Broil until frittata is puffed and cheese begins to turn golden, about 3 minutes. Cut into wedges and serve.