3	tablespoons (38 g) reduced-fat margarine, softened

1/4	cup (48 g) packed light brown sugar

1/2	teaspoon (2.5 ml) ground cinnamon

1/4	teaspoon (1.75 ml) ground ginger

1/4	teaspoon (1.75 ml) salt

1/8	teaspoon (0.6 ml) ground allspice

1	large egg yolk

2	cups (390 g) mashed cooked sweet potatoes

1	cup (240 ml) evaporated skim milk

3	large egg whites

1	9-inch (22.5 cm) unbaked pie shell

1. Preheat oven to 350°F (180°C), Gas Mark 4.
2. In a large bowl, beat together margarine, brown sugar, cinnamon, ginger, salt, allspice, and egg yolk. Whisk in sweet potatoes and evaporated milk.
3. In a medium bowl, beat egg whites until stiff. Fold into sweet potato mixture. Pour into unbaked pie shell.
4. Bake 40 to 45 minutes, until a tester inserted in center comes out clean. Cool on a rack until ready to cut into wedges to serve.