Begin by flattening the steaks with a rolling pin and trimming any excess fat. Season both sides with salt and pepper.
In a skillet large enough to hold all four steaks in a single layer, heat a bit of olive oil. Sauté the steaks quickly for about a minute on each side, then remove them from the pan and let them rest.
For the sauce, heat some olive oil in a separate pan. Slice the shallots and add them to the pan, allowing them to soften briefly.
Next, slice the mushrooms and add them along with a tablespoon of butter. Crush the garlic and add it to the mixture.
Stir in the Worcestershire sauce and then the Dijon mustard, heating everything through for about a minute.
Increase the heat and tilt the pan away from you. Carefully pour the brandy into the far end of the pan and allow it to ignite, taking care to avoid any flames that might singe your eyebrows.
Once the alcohol has burned off, swirl the juices in the pan. Add the heavy cream and let the sauce thicken before reducing the heat.
Return the steaks to the pan and cook them further according to your desired doneness.
Chop the parsley and stir half of it into the sauce.
