A classic, made all the more delicious by using Comté.
Put the grated Comté into a medium bowl.
Simmer the Guinness in a saucepan until it has reduced by half, then add the cream and reduce again by half until it is really thick. Pour this over the Comté and add the mustard, Worcestershire sauce and egg yolks with a twist of black pepper (the mixture is salty enough so you do not need to add salt).
Heat the grill to medium and toast the bread on both sides.
Spread the cheese mixture evenly in a layer about 1cm thick over one side of each slice of toast (right up to the edges to avoid the bread burning), then place on a baking tray about 10cm beneath the grill for about 4 to 5 minutes until the topping is bubbling and nicely browned.