Well, Alton Brown instructs us to:
In a medium saucepan over low heat, melt the butter and whisk in the flour. Cook, whisking constantly for 2 to 3 minutes, being careful not to brown the flour. Whisk in mustard, Worcestershire sauce, salt, and pepper until smooth. Add beer and whisk to combine. Pour in cream and whisk until well combined and smooth. Gradually add cheese, stirring constantly, until cheese melts and sauce is smooth; this will take 4 to 5 minutes. Add hot sauce. Pour over toast and serve immediately.
From webpage
You might want to try this recipe from the BBC.
I’ve just been melting cheese over bread. It’s plenty good.