Traditional Welsh Rarebit

Melt butter in a saucepan and stir in flour to make a roux; cook for a minute.

Gradually whisk in warm beer (ideally a dark ale or stout) to make a thick, smooth sauce.

Add grated mature cheddar cheese and stir over low heat until melted.

Season with English mustard, Worcestershire sauce, and a pinch of cayenne pepper.

Toast thick slices of crusty bread on one side.

Spread the cheese mixture thickly over the untoasted side.

Place under a hot grill (broiler) for a few minutes until the cheese is bubbling and golden brown.

Serve immediately.