In a small skillet over medium-low heat, melt the remaining 1/4C butter. Add the flour and cook, stirring, until lightly browned (about 2 minutes). Whisk this roux into the soup until incorporated, and bring to a simmer. Cook until thickened (about 8 minutes). Add the cream, cheeses and remaining lager and simmer, stirring occasionally, until thick and creamy (about 5 more minutes). Season with salt & pepper to taste. If the soup is too thick, add a little more broth.