Preheat the oven to 375°F. In a large bowl, whisk together the flour, sugar, baking soda, and salt. Add the butter and cut in with a pastry cutter until the pieces are no larger than small peas. In a small bowl, combine the egg with the buttermilk and pour the mixture over the dough. Stir together the mixture with a rubber spatula until there is no uncombined flour on the bottom of the bowl. If you see a lot of loose flour, add one or two tablespoons more buttermilk and mix again.
Dump the dough out onto a work surface and use your hands to gather it together into a mound, then flatten into a disk. At this point, it may be necessary to knead it a little to get it to hold together. Don't knead it any more than necessary for it to hold together in a loose shaggy mass. Roll it out into a 3/4-inch-thick disk. Use a 3 1/4-inch cookie cutter to cut out the shortcakes and arrange them on a parchment paper-lined sheet pan. Brush each of the shortcakes with buttermilk and sprinkle over the turbinado sugar.
Bake for about 20 minutes, or until pale brown.
Just before serving, slice the shortcakes in half horizontally with a serrated knife. Arrange the strawberries over the bottom halves of the shortcakes - work directly over the serving plates so there is less transferring - and dollop the whipped cream over them. Put on the lids and serve.