Place the peppercorns into a shallow bowl. Sprinkle the eye fillets with salt on both sides and coat both sides with crushed peppercorns.
Melt the butter with the olive oil over high heat in a heavy frypan (not nonstick) until the foam disappears from the butter. Gently place the steaks in the pan and cook until they start to become firm and are reddish-pink and juicy in the centre, about 3 1/2 minutes per side. Remove the steaks to platter and cover tightly with foil.
Pour the beef stock into the frypan and use a whisk to stir the stock and scrape up any dissolved brown flavour bits from the frypan. Whisk in the cream and simmer the sauce until it's reduced and thickened, 6 to 7 minutes. Place the steaks back in the frypan, turn to coat with sauce, and serve with the remaining sauce.