Melt 20 g salted butter in pan then add 1 shallot (finely chopped) and 100 g chestnut mushrooms (sliced), cook until softened - 5 minutes
Pour in 50 ml brandy and set it alight (using a match or BBQ lighter etc. just be careful of your eyebrows!) - see Note 1
Add 2 cloves garlic (finely chopped) and fry for 1 minute
Stir through 1 tablespoon worcestershire sauce and 1 teaspoon dijon mustard
Add 100 ml double cream, 100 ml whole milk, pinch black pepper - simmer for 5 minutes
Finally, switch off the heat and add handful fresh parsley (finely chopped) just before serving
Pour liberally over your steak of choice!
Notes
Note 1: if you don't want to set the brandy alight, you could turn the heat up on the hob/cooker and cook off the alcohol rather than burning it off. You'll be left with a slightly different taste, but equally effective outcome. I love the flambé process as it adds a little drama and is very effective!