Preheat oven to 400°F. Spray 10-inch-diameter glass pie dish with oil spray. Separate salmon into chunks, leaving bones intact (bones are very soft and will blend into potato mixture). Remove black pieces of skin; discard. Set salmon aside.
Cook potatoes in large pot of boiling salted water until very tender, about 20 minutes. Drain. Transfer potatoes to large bowl. Add milk, goat cheese and 2 tablespoons Parmesan cheese. Using electric mixer, beat until almost smooth. Season with salt and pepper. Beat in eggs. Stir in salmon and green onions. Transfer mixture to prepared dish. Sprinkle with remaining 1 tablespoon Parmesan cheese.
Bake casserole until golden and heated through, about 45 minutes.
Per serving: calories, 330; total fat, 11 g; saturated fat, 5 g; cholesterol, 150 mg Nutritional analysis provided by Bon Appétit