Preheat the oven to 425 degrees. Grease a 9” round cake pan.
Place the strawberries in a medium bowl, toss with ⅓ cup white sugar. Set aside.
In a large bowl, stir together the flour, baking powder, ¼ cup white sugar, salt, and lemon zest.
Cut the shortening into the flour mixture using a pastry blender or forks until it resembles coarse crumbles.
In a small bowl, mix together the egg, milk and vanilla. Pour this mixture into the flour mixture. Stir to combine. The mixture will be dough-like and thick.
Spread the batter into the greased pan. Spread it to the edges of the pan in one even layer. Bake for 15 - 20 minutes, until a toothpick comes out clean and the top is lightly golden brown. Let the cake cool 15 minutes in the pan on a wire rack.
Let the cake cool 15 minutes in the pan on a wire rack. Remove shortcake from the pan and place directly on cooling rack for an additional 10 minutes.Use a sharp knife to slice it in half horizontally across the middle (to make two cake layers). Gently move the top layer to the cooling rack. Cool both layers completely (aproximately 15 minutes).
Whip the heavy whipping cream using a mixer until stiff peaks form.
Spread the bottom half of the cake with half of the whipped cream. Using a slotted spoon, spoon on half of the strawberries. Add the 2nd layer of cake and top with the remaining whipped cream and strawberries.
Serve within an hour of making for best results.