Preheat oven to 450°.
Heat a large nonstick skillet over medium heat. Coat pan with cooking spray. Add mushrooms and leek; cook 6 minutes or until leek is tender, stirring frequently.
Combine milk and next 5 ingredients (milk through eggs) in a large bowl, stirring with a whisk. Add leek mixture, pasta, and basil; toss gently to combine.
Heat pan over medium-low heat. Coat pan with cooking spray. Add egg mixture; cook until edges begin to set (about 4 minutes). Gently lift edge of egg mixture, tilting pan to allow some uncooked egg mixture to come in contact with pan. Cook 5 minutes or until almost set. Sprinkle evenly with cheese; wrap handle of pan with foil. Bake 7 minutes or until golden brown. Cut into 8 wedges.