Heat 1 tbsp of olive oil in a large skillet. Once hot, add the pork medallions and sear, undisturbed, for 5 minutes.
Flip the pork and cook an additional 3 - 5 minutes, until seared. Remove to a plate and keep warm. NOTE: The pork will finish cooking in the sauce.
Add the remaining 1 tbsp olive oil to the pan and cook the onion for 2 -3 minutes, until translucent.
Add the garlic and cook an additional minute, until fragrant.
Add the mushrooms and rosemary and brown over medium heat, cooking appropriately 8 minutes. Season with salt and pepper as needed.
Sprinkle in the flour and stir to coat the veggies.
Deglaze the pan with the Marsala wine and cook over medium heat for about 5 minutes until it's reduced by about half.
Add the stock and pork then cook for an additional 5 - 7 minutes, until pork is cooked through.
Remove from heat, stir in the cream. Season with salt and pepper to taste.
Serve over mashed potatoes, rice or pasta.