In the top of a double boiler, heat the butter until it begins to brown. Add the milk and heat until very hot. Add the cheese slowly and allow it to melt completely. Add the mustard and combine. Season with pepper.
In a small bowl beat the eggs. Add several tablespoons of the hot cheese mixture to the eggs. Add the warmed eggs to the pot of melted cheese and stir. Add the stout, stir to combine and heat for 2 minutes more.
Pour the cheese over the toast. Serve with fruit and nuts.