Gather all ingredients.

Pat steaks dry with paper towels; season on both sides with sea salt.

Place whole peppercorns on a wooden cutting board, and crack peppercorns with an iron skillet or heavy pan. Lightly pound peppercorns, then rub peppercorns in a circular motion over the cutting board until pieces are fairly uniform, and more coarse than ground black pepper. Press cracked pepper into both sides of steaks; let stand at room temperature for about 20 minutes.

Heat butter and olive oil in a 10-inch iron skillet over medium-high heat. When butter stops sizzling and oil is hot, reduce heat to medium and carefully add steaks to the hot oil. Cook about 3 minutes per side, or until an instant-read thermometer measures 120 degrees F (50 degrees C) for medium-rare.

Remove steaks from pan; tent with aluminum foil to keep warm. To the same skillet, over medium-low heat, add minced shallots and cook until softened, about 2 minutes. Add garlic and thyme sprigs; cook until fragrant, about 20 seconds.

Remove the pan from heat and slowly and carefully pour in the cognac. Return the pan to the burner and stir to combine. Cook until the liquid is evaporated.

Stir in cream; continue cooking until sauce thickens enough to coat the back of a spoon.

To serve, spread sauce on a serving platter. Slice steaks thinly on the diagonal, and place on the sauce. Garnish with additional thyme sprigs, if desired.