1 Grease a large baking sheet. Set aside. Chill a medium mixing bowl and the beaters of an electric mixer.
2 Drain sweet potatoes, reserving 2 tablespoons of the syrup. Mash enough of the sweet potatoes to make 1/2 cup. (Cover and refrigerate any remaining sweet potatoes and syrup to heat later as a side dish.)
3 In a medium mixing bowl stir together the mashed sweet potatoes, the reserved syrup, the milk, and melted margarine or butter. Sprinkle the biscuit mix, 2 tablespoons sugar, and cinnamon over sweet potato mixture; stir just until dough clings together. (The dough might have some lumps and should be thick.)
4 Drop dough onto the prepared baking sheet in 8 equal portions. Bake in a 425° oven about 12 minutes or until golden brown. Transfer to a wire rack and allow to cool slightly.
5 Meanwhile, in a large mixing bowl combine fresh berries and the 3 tablespoons sugar. Set aside. In the chilled mixing bowl beat the whipping cream and the 2 tablespoons sugar with an electric mixer on medium speed until soft peaks form (tips curl).
6 To serve, split each shortcake in half crosswise; place bottom halves on 8 dessert plates. Top with some of the berries and some of the whipped cream. Place a shortcake top on each serving. Top with the remaining berries and the remaining whipped cream.