COOK bacon, leeks and garlic in large saucepan on medium-high heat 7 to 9 min. or until bacon is crisp, stirring frequently. Drain; discard drippings. Return bacon mixture to pan.
STIR in flour; cook and stir on medium heat 1 min. Gradually stir in milk; cook 8 min. or until slightly thickened, stirring frequently.
ADD VELVEETA; cook 5 min. or until completely melted, stirring frequently. Stir in beer; cook 2 min. or until heated through, stirring occasionally. Serve topped with parsley.