Preheat your oven to 200C (400F) and line a baking sheet with parchment paper. Set this aside.
Before you start, ensure you have these things done and set aside:Chop the berries for the shortcake dough (I diced the strawberries but left the blueberries whole). Grate the butter and put in the freezer until you need it.Mix the buttermilk, heavy cream, vanilla extract and sourdough starter together in a jug. Now in a large mixing bowl, add together the all purpose flour, baking powder, baking soda, salt and sugar. Stir together until well combined.
Now put the cold, grated butter into the flour mixture and rub it into the flour. You won't need to rub it a lot because the butter is grated, so as long as it's well distributed and coated in flour it will be fine.
Now, pour the buttermilk mixture (wet ingredients) and the chopped berries into the dry ingredients and stir together to form a firm, wet dough. It should be "scoopable".
Now take the tray you prepared earlier and a cookie scoop and scoop 15 balls of dough. Arrange them in a 3 x 5 formation on the tray. They should be touching.
Brush the dough balls with melted butter and sprinkle with the raw sugar.
Bake the sourdough berry shortcake in the oven at 200C (400F) for 30 minutes. Once they are golden brown and baked through, remove from the oven and allow to cool. While the shortcake is cooling, prepare the toppings.
Whip the heavy cream and vanilla extract together until soft peaks form. You can add some powdered sugar to the cream if you prefer, but the shortcakes already have quite a bit of sugar.
Once the sourdough berry shortcake is cool, carefully transfer it to a serving platter. Top with the whipped cream and arrange the berries on top.