Add 1 tablespoon butter to a skillet.
Reduce the heat to medium high and add the shallot, garlic and chopped rosemary.
Cook, stirring, 30 seconds.
Add the mushrooms and cook until tender, about 3 minutes.
Add the Tawny Port, cook until reduced by half, about 2 minutes.
Add the chicken broth; cook until thickened, about 4 minutes.
Add grilled or pan-seared steaks and any accumulated juices and the remaining 1 tbsp butter to the skillet.
Cook, turning the steaks to coat, 1 minute.
Serve with the cauliflower puree, creamy polenta, or mashed potatoes.