Lemony Strawberry Shortcakes

For Shortcakes: Grease a cookie sheet. Combine flour, 3 tablespoons sugar, baking powder, and salt. Cut in unsalted butter and mix until crumbly. Mix milk, egg, and lemon zest. Gradually add to flour mixture until moistened. Gently knead dough until it holds together, pat dough until 1/2 inch thick. Cut out circles with a 3-inch cookie cutter, transfer to a cookie sheet. Re roll scraps to make 6 circles total. Brush tops with 1 tablespoon heavy cream; sprinkle with 1 tablespoon sugar. Bake 18 to 20 minutes at 400 degrees F; cool on rack. For Strawberries: Crush whole strawberries and 3 tablespoons sugar. Stir in sliced strawberries and lemon juice. Let stand 20 minutes. For Whipped Cream: Beat 3/4 cup heavy cream, 1 tablespoon confectioners' sugar, and vanilla extract until stiff. To serve, split shortcakes; top with strawberry mixture and whipped cream; replace tops.