Preheat the oven to 500 degrees F.
In a cast iron skillet, season the filets with salt/pepper.
Slice butter and lay on top.
Decorate bottom of pan with rosemary, sage, garlic.
Roast until cooked to your liking. (I did about 130 degrees, let it rest, sliced and cooked slices one minute longer in cast iron pan)
For the sauce, use the same skillet from the beef.
Mash the garlic down with a fork. Add shallots
Stir in flour and cook 1 min.
Pour in broth on med-high heat and scrape bottom. Add cream and parmesan cheese
Simmer on low.
Lay some beef slice in sauce, top with crostini and more beef.
Top with parsley and dig in!