Cut the fillet into 3 cm thick slices (not thinner!). Finely chop the rosemary needles. Put the mustard, rosemary, cream and pepper on a plate, turn the meat slices in it, wrap tightly with the ham. (You can also wrap the whole fillet in ham instead of the slices.) Sear it in hot olive oil.
Reduce the heat, deglaze with white wine and brandy. Remove the fillet and keep it warm in the oven. Pour in the cream, let it boil down for 5 - 10 minutes. Season the sauce with salt, pepper, sugar, mustard, rosemary and a little garlic. Then put the fillet slices back into the sauce and let them steep for about 10-15 minutes so that the meat turns pink on the inside.
This goes well with rice or baguette, possibly also spaetzle.