In a large frying pan, heat up some olive oil (medium heat) + add the shallots and rosemary, until they soften, then add all the mushrooms, grated garlic and peppercorns.
Sweat them down until mushrooms have softened, but still keep their texture. Remove from pan and set aside for later.
Then, whack up heat, cook steak to your liking with salt/pepper – then remove steaks, wrap in foil, and keep in warm place (for me, oven @ 40-50 degrees C works well – do not overheat the oven otherwise you’ll cook the steaks too much). Alternatively, an warmed plate pre-heated in the oven works well.
Let the frying pan cool down a little, and return mushroom/shallots. Warm up the pan (making sure ingredients do not burn) then add the brandy, and as it starts to bubble ignite (keeping an eye on hair/eyebrows etc ;o) Once flames have subsided, reduce the heat and slowly pour in the cream. (if too hot, the cream will cook which spoils it a little).
As the cream warms through the other ingredients, add the Dijon mustard and stir through. Season to taste.
Remove steaks from foil and pour sauce on top of them. Serve immediately on oven warmed plates.