To prepare the fruit: Mash 2 cups of the strawberries. Slice the remaining strawberries, and mix all of the berries with the sugar and lemon juice. Let rest 1 hour., Preheat the oven to 425°F. Lightly grease a baking sheet, or line it with parchment., To make the biscuits: Whisk together the dry ingredients, and work in the cold butter or shortening until the mixture is crumbly., Whisk the vanilla and egg with the milk, then add all at once to the dry ingredients and stir until the liquid is absorbed., Turn the dough out onto a lightly floured surface and knead four or five times, just until it holds together. Pat the dough out until it's about 1/2" to 3/4" thick, and cut it into 2 1/2" to 3" circles., Place the biscuits on the prepared baking sheet, brush the tops with milk for a shiny surface, and sprinkle with sugar., Bake for 10 to 12 minutes, until the tops are golden brown. Remove them from the oven and cool for 15 minutes before serving., To assemble the shortcakes: Whip the cream until soft peaks form., Just before serving, split open the biscuits, spoon half the berries and whipped cream on the bottom half, top with remaining biscuit halves, and spoon on the remaining berries and cream.