Instructions

Microwave ½ cup broth and porcini mushrooms in covered bowl until steaming, about 1 minute. Let sit until softened, about 5 minutes. Drain porcini mushrooms in fine-mesh strainer lined with coffee filter, reserve liquid, and chop porcini mushrooms fine.
Heat 1 tablespoon oil in 12-inch nonstick skillet over medium-high heat until shimmering. Add cremini mushrooms, ¼ teaspoon salt, and ¼ teaspoon pepper and cook, covered, until mushrooms release their liquid, about 3 minutes. Uncover and continue to cook, stirring occasionally, until liquid has evaporated and mushrooms are well browned, about 8 minutes longer. Transfer to bowl; cover to keep warm.
Pat steaks dry with paper towels and season with salt and pepper. Add 1 tablespoon oil to now-empty skillet and heat over medium heat until just smoking. Add steaks and cook until well browned on first side, about 4 minutes. Flip steaks and cook until well browned on second side and meat registers 125 degrees (for medium-rare), 4 to 6 minutes. Transfer steaks to carving board and tent with aluminum foil.
Heat remaining 1 tablespoon oil in now-empty skillet over medium-high heat until shimmering. Add shallot, flour, garlic, rosemary, porcini mushrooms, ¼ teaspoon salt, and ¼ teaspoon pepper and cook until shallot is beginning to soften, about 1 minute. Stir in ¾ cup Marsala, reserved porcini mushroom soaking liquid, and remaining ½ cup broth. Cook until reduced to 1 cup and slightly thickened, 5 to 7 minutes.
Reduce heat to low and whisk in butter, 1 piece at a time, until emulsified. Stir in parsley, lemon juice, cremini mushrooms, and remaining 1 tablespoon Marsala. Season with salt and pepper to taste. Slice steaks thin and transfer to warm platter. Spoon sauce over steaks and serve.