Meanwhile, in 4-quart saucepan or Dutch oven, melt 1/2 cup butter over low heat. Add garlic; cook 30 seconds, stirring frequently. With wire whisk, stir in flour and salt until smooth. Increase heat to medium; cook, stirring constantly, until mixture is smooth and bubbly. Gradually stir in milk. Heat to boiling, stirring constantly. Boil and stir 1 minute. Stir in cheeses. Cook until melted, stirring occasionally. Stir pasta and parsley into cheese sauce. Pour mixture into baking dish.