Preheat a medium sized cast iron skillet over medium-high heat and drizzle with olive oil.
Pat the steaks dry with paper towels and evenly season the steaks with salt and pepper on all sides and dredge in flour, shaking off the excess.
Once the skillet is hot, sear the steaks for 2 minutes per side until both sides are deeply charred, then remove and set aside to a plate.
In the same skillet, lower the heat to medium add butter and more olive oil if needed and the sliced mushrooms. Saute the mushrooms for 4-5 minutes until they begin to deepen in color.
Add the chopped shallots and continue sautéing for another 2-3 minutes until the shallots begin to soften and become fragrant.
Add the chopped garlic and herbs and continue sautéing for another 1-2 minutes.
Pour the marsala wine in and let the wine reduce slightly, while scraping the bottom of the skillet.
Then pour in the chicken stock and bring everything up to a strong simmer and let the liquid reduce for 1-2 minutes.
Pour in the heavy cream and 1 tablespoon of butter and stir everything together. Nestle the steaks back into the creamy marsala sauce, with any accumulating juices and baste the sauce onto the steak.
Continue cooking on a low simmer until the sauce has thickened slightly and to warm through the steaks, for another 3-4 minutes.
Once done, remove from the heat and let the steaks rest for at least 5 minutes before slicing. Garnish with finely chopped parsley and serve the steak marsala with the creamy mushroom sauce.