My current favourite steak sauce

• 250g chestnut or other mushrooms
• 150ml double cream
• 1/2 a good sized red onion
• 2 cloves of garlic
• 25g Parmigiano reggiano
• heaped teaspoon of wholegrain mustard
• good splash of brandy
• butter
• olive oil
• copious seasoning

Gently heat enough butter and oil to cover the bottom of a good solid pan. Very finely dice the onion and garlic and slowly start them sweating. Finely slice the mushrooms and add them to the pan and put on a lid. Keep an eye on the pan while you do everything else for the meal, agitating occasionally and for a minimum of 15 minutes if you are doing something real quick. While resting the meat, take off the heat and stir in first the brandy then the cream and finally the cheese and mustard. Season to taste (I tend to a little salt and quite a bit of pepper, most from my black pepper mill set to cause, some from the bill with a mix of Bristol 5 pepper blend and dried chilli flakes). Return to a gentle heat to warm the sauce back through and melt the cheese.