English-Style Cod & Potato Pie

Preheat oven to 425°F (220°C). Cover potatoes and garlic with cold water in large saucepot. Bring to a boil over high heat. Reduce heat to low and simmer uncovered until potatoes are tender, about 15 minutes; drain. Beat potatoes, 30 mL Becel® Buttery Taste margarine* and 125 mL milk with electric mixer on low speed or with potato masher until smooth. Evenly spread mashed potatoes on bottom and up sides of 1.5 L baking dish; set aside. Melt remaining 15 mL margarine in large nonstick skillet over medium-high heat and cook mushrooms with onion, stirring occasionally, until tender, about 6 minutes. Stir in remaining 375 mL milk, Knorr ®Alfredo Pasta Sauce mix and thyme and simmer, stirring frequently, until thickened, about 3 minutes. Stir in peas and sherry. Simmer 1 minute. Arrange cod on potatoes in prepared baking dish. Season, if desired, with black pepper and a squeeze of lemon. Pour sauce mixture over cod. Bake 40 minutes or until cod flakes with a fork and bubbling.