PREHEAT oven to 400° F. Grease 13 x 9-inch baking dish.
COOK pasta shells according to package directions, adding frozen peas to boiling pasta water for last 30 seconds of cooking time; drain.
COMBINE salmon, evaporated milk, soup, 1 1/4 cups cheese, black pepper and garlic powder in large bowl until well blended. Add pasta and peas; stir until combined. Cover dish tightly with foil.
BAKE for 20 minutes or until heated through. Remove foil; sprinkle with remaining 1/4 cup cheese. Let stand for 5 minutes before serving.