Special equipment: a pastry blender and a 3-inch biscuit cutter, optional
For the strawberries: In a medium bowl, mix the strawberries and granulated sugar. Set aside, covered, for at least 30 minutes and up to 3 hours in order for the sugar and strawberries to a make a sauce. The longer this sits, the juicier the strawberries will become.
For the shortcakes: Preheat the oven to 450 degrees F. Grease a baking sheet with cooking spray.
In a large mixing bowl, combine the flour and butter. Using a pastry blender, cut the butter into the flour until it resembles coarse meal. Stir in the baking powder, salt, granulated sugar and baking soda. Make a well in the center and pour in the buttermilk. Mix with a fork until all of the ingredients are incorporated and the dough begins to shape into a ball. (The dough will be slightly dry.)
Sprinkle a work surface with flour, coat your palms and rub some on a rolling pin. Turn out the dough onto the work surface. Knead the dough for 1 to 2 minutes, folding it over onto itself each time. Roll the dough to about 1/2 inch thick. Flour a 3-inch biscuit cutter (or the rim of a glass) and cut out the biscuits. Reshape the leftover dough into a ball, roll it out again and cut out more biscuits until there is no dough remaining.
Put the biscuits on the prepared baking sheet, brush the tops with the heavy cream and sprinkle with the turbinado sugar. Bake until the tops are golden brown, 10 to 12 minutes. While the biscuits are still hot, spread some softened butter on top of each one with a pastry brush and let it melt. Spoon some of the strawberries and their sauce on top of each biscuit and serve.
The recipe calls for butter, but I also like to substitute Smart Balance spread. It gives the same texture to the biscuits as shortening.