Heat oven to 350. Cook pasta according to package; drain. Whisk together remaining shell ingredients. Add pasta; toss. Arrange in 9" pie dish, pressing to form shell. Heat large skillet over medium heat until hot. Add beef; brown 4-5 minutes, breaking up into 3/4 crumbles. Pour off drippings. Season with garlic, salt and cumin; stir in salsa. Bring to a boil. Cook 3-5 minutes or till liquid is almost evaporated, stirring occasionally. Reserve 2 T. beef mixture for garnish. Stir sour cream into remaining beef; spoon into shell. Place 1 cup cheese in center, leaving 2" border around edge. Spoon reserved beef mixture onto center of cheesel; bake 15 minutes or until heated through.