In a small bowl whisk together the flour, baking powder, and salt. In a large bowl of a stand-alone KitchenAid, whisk together the melted butter and sugar. Once well-incorporated whisk in the eggs one at a time and the egg yolk, then vanilla extract, and buttermilk.
Using a spatula gently fold the dry ingredients into the egg butter batter until all the flour is well mixed in. Transfer the batter to the prepared pan. Add the raspberries evenly over the top and generously sprinkle the cake with Turbinado sugar.
Bake for 45 to 50 minutes or until a toothpick inserted in the middle comes out clean. If using a regular oven, turn the cake halfway through.
Let the cake cool in the pan over a wire rack for 10 minutes. Use the parchment paper to lift the cake out. Let it cool completely. Serve it with dollops of whipped cream.