Heat the olive oil in a cast-iron skillet over medium-high heat. Once hot, add the filet mignons and sear each side for about 3-4 minutes, depending on the thickness of the steak. Use tongs to turn the steaks and sear evenly.
Remove the steaks from the pan and set aside to rest. In the same pan, add the butter and shallots. Cook for 2-3 minutes until fragrant and soft. Add the brandy or cognac and let it reduce by half.
Lower the heat and add the heavy cream, stirring constantly until the sauce thickens slightly. Taste and adjust seasoning with salt and freshly cracked pepper.
Place the steaks on plates, spoon the creamy pepper sauce over them, and serve immediately.