Melt butter in large saucepan on medium heat. Sprinkle with flour and Seasoning Mix. Cook and stir 1 minute. Slowly whisk in milk and beer until smooth. Stirring constantly, cook 5 minutes or until sauce starts to thicken. Gradually whisk in cheeses until melted and smooth.
Transfer cheese mixture to warm fondue pot or slow cooker to keep warm, if desired.
