Remove the steaks from the refrigerator for at least 30 minutes and up to 1 hour prior to cooking. Sprinkle all sides with salt.
Coarsely crush the peppercorns with a mortar and pestle, the bottom of a cast iron skillet, or a mallet and pie pan. Spread the peppercorns evenly onto a plate. Press the fillets, on both sides, into the pepper until it coats the surface. Set aside.
Melt the butter and olive oil in a 10-inch carbon-steel pan over medium heat. As soon as the butter and oil begin to turn golden and smoke, gently place the steaks in the pan. For medium-rare, cook for 4 minutes on each side. Once done, remove the steaks to a plate, tent with foil and set aside. Pour off the excess fat, but do not wipe or scrape the pan clean.
Off of the heat, add 1/3 cup Cognac to the pan and carefully ignite the alcohol with a long match or firestick. Gently shake pan until the flames die. Return the pan to medium heat and add the cream. Bring the mixture to a boil and whisk until the sauce coats the back of a spoon, 5 to 6 minutes. Add the remaining teaspoon of Cognac and season to taste with salt. Add the steaks back to the pan, spoon the sauce over, and serve.