In a large skillet, combine fresh blackberries, granulated sugar, water, lemon juice, ground cinnamon, and vanilla extract. Stir well and bring to a gentle simmer, watching for the berries to start releasing their juices, about 5 minutes.

In a medium bowl, whisk together sifted flour, baking powder, a pinch of salt, and additional sugar until well combined.

Cut cold unsalted butter into small pieces and incorporate into the dry mixture using a pastry cutter until crumbly.

Mix buttermilk with vanilla extract in a separate bowl and combine with the flour mixture until just moistened.

Scoop and drop dollops of dough into the simmering sauce, ensuring even distribution.

Cover the skillet, reduce heat to low, and simmer for 12-14 minutes until dumplings are puffed and cooked through.

Let cool for a few minutes before serving; top with whipped cream or vanilla ice cream.