Remove the steak 30 minutes prior to cooking to allow it to come to room temperature. Preheat a grill over medium-high heat.
Heat the olive oil in a large skillet over high heat. Add the mushrooms, season with salt and pepper and cook until browned, 8 to 10 minutes.
While the mushrooms are cooking, sprinkle the steak generously with salt and pepper. Place half the bay leaves and rosemary onto the grill, place the steak on top and cook for 3 to 4 minutes. Place the remaining bay leaves and rosemary on the grill and flip the steak on top. Cook to medium, another 3 to 4 minutes. Remove and let rest for 5 minutes before slicing against the grain into thin slices.
While the steak is resting, add the brandy to the mushrooms, making sure to turn off the heat before adding. Return to the heat and let cook for 1 minute, scraping up the little brown bits from the pan. Add the cream, stir and turn the heat down to medium low. Let simmer until thickened, about 5 minutes. Taste and adjust the seasoning if necessary.
Place the sliced steak onto a platter. Pour the mushroom sauce over top and serve immediately.
NotesIf you cannot find fresh porcini mushrooms, you can substitute shiitakes or cremini. You can also use 4 ounces of dried porcinis. Rehydrate the mushrooms in 2 cups hot water for about 5 minutes. Drain, making sure to reserve the water. Pat the mushrooms dry and cook as directed above, but reduce the cooking time to about 5 minutes. Also, substitute 1/4 cup of the reserved mushroom liquid for 1/4 cup of the cream.