In a large skillet, combine blackberries, granulated sugar, water, lemon juice, ground cinnamon, and vanilla extract. Place over medium heat and stir until the mixture simmers, about 5 minutes.

In a mixing bowl, whisk together flour, baking powder, salt, ground cinnamon, and sugar. Cut in butter until it resembles coarse crumbs. Stir in buttermilk and a splash of vanilla until just moistened.

Once the blackberry sauce is bubbling, drop spoonfuls of the dumpling dough into the sauce. Cover and reduce heat to low, simmer for 12-14 minutes until dumplings are fluffy.

Carefully spoon blackberry dumplings into bowls with sauce. Serve warm topped with ice cream or whipped cream.