Put the soft butter in a bowl and add half the Saint Agur. Mash together until smooth.
Work in the parsley, Tabasco and a good milling of black pepper.
Break the remaining Saint Agur into small pieces and fold it in to the seasoned butter along with the walnuts.
Check the seasoning and adjust, if you wish.
Roll the butter up into a log in greaseproof paper, transfer to the fridge and chill until firm - about an hour.
Bring the two steaks up to room temperature.
Season the steaks with salt and pepper. Heat a splash of oil in a frying pan, or brush the steaks with oil and grill on a griddle. Cook the steaks briskly for two minutes on each side (for rare to medium rare). I cook mine for 8 minutes, turning every two minutes, for my perfect steak.
Remove from the pan and ret in a warm place for five minutes.
To serve, put the steaks on warm plates and garnish with a couple of slices of the Saint Agur butter.
A garnish of a watercress salad with some chopped shallot tossed through would be a fine accompaniment.
Food waste prevention tip: store any remaining butter in the freezer, slicing off the amount you need straight from the freezer. This will keep for several weeks.