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.