1. Boil potatoes until soft. Mash with 1/4 cup milk, garlic and 1 tbsp. butter. Keep warm.
2. To make Marsala wine sauce, melt 2 tbsp. butter in saucepan. Add 2 cups milk, salt, sugar, lemon juice mushrooms and wine. Bring to boil and reduce to desired consistency.
3. Grill filets to desired temperature.
4. Serve with potatoes and sauce.