This recipe for welsh rarebit is an adaption of Keith Floyd's (former 3 RTR officer IIRC) and is an old favourite of mine:
50ml Double cream
175g cheddar cheese, grated try to use a strong, mature cheddar
150ml beer (not lager)
1 tsp Dijon mustard
2 tsp Worcestershire sauce
salt and pepper
2 egg yolks
4 slices of toast - must be thick
1. Make a roux with the butter and flour, and leave to cool.
2. Mix the cream and milk together, bring it to the boil, then whisk it into the roux. Bring to the boil once again, whisking to ensure that it does not burn and also that the sauce is free of lumps.
3. Add the cheese, fold in and remove from the heat.
4. In a seperate pan, reduce the ale, mustard and Worcestershire sauce. When thick, add this mixture to the cheese sauce. Season well with salt and pepper and beat in the egg yolks. Be careful not to cook the eggs, just mix them in.
5. Spoon on to the slices of toast and grill until hot (bubbling).