In a 9" or 10" cast iron skillet or a cooking skillet, combine the blackberries, sugar, water, lemon juice, cinnamon, and vanilla extract. Stir to combine.
1 pound (454g) blackberries, 1 cup (200g) granulated sugar, 1 cup (240mL) water, 1 Tablespoon (15mL) lemon juice, ½ teaspoon ground cinnamon, ½ teaspoon vanilla extract
Turn the heat to medium, and allow fruit mixture to come to a simmer while you make the dumpling dough.
DUMPLINGS
In a medium size bowl, whisk together the sifted flour, baking powder, ground cinnamon, salt, and sugar.
2 cups (240g) sifted flour1, 3 teaspoons baking powder, ½ teaspoon ground cinnamon, ½ teaspoon salt, ¼ cup (50g) granulated sugar
Add the butter to the flour mixture, then, using a pastry blender, work the butter into the mixture until it becomes coarse, uneven crumbs. Aim for pea-sized chunks (some smaller or larger are fine, but overall, the size should be pea-sized).
6 Tablespoons (85g) unsalted butter
Pour the vanilla extract into the buttermilk, stir to mix well, and then pour the buttermilk/vanilla mixture evenly over the flour/butter mixture. Stir just until the dry ingredients are moistened3 and create a shaggy dough.
¾ cup (180mL) buttermilk2, ½ teaspoon vanilla extract
ASSEMBLY & COOKING
Drop the dumpling dough by Tablespoonfuls into the simmering blackberry mixture, spreading them out evenly over the whole skillet. I used this #50 cookie scoop.
When you have scooped all the dough into the blackberries, cover the skillet with its lid or foil and reduce the heat to low.
Allow the dumplings to simmer for about 12-14 minutes, until the dumpling balls are cooked all the way through. Internal temperature should be at least 195ºF (91ºC). You can test one with a digital thermometer-- this is my very favorite instant-read digital thermometer, and this is my favorite budget-friendly digital thermometer. Be on the lookout for liquid bubbling over. This isn't going to be a problem for the recipe, but can burn you if you touch it. Resist the temptation to peek under the foil so the heat and moisture remain inside the "tent" to keep the dumplings cooking properly.
When dumplings are cooked all the way through and blackberry mixture has thickened, remove from the heat and allow to cool a few minutes before serving. To serve, spoon the hot dumplings and blackberries into bowls, then serve with ice cream, whipped cream, or as is. Store leftovers covered in the refrigerator, up to 4 days. Dumplings freeze well, up to 3 months. Thaw in the refrigerator and heat individual servings in the microwave as needed.
Notes
Flour: you can use all-purpose or bread flour. “Sifted flour” means sift it and then measure it.
Buttermilk: if you don't have buttermilk, you can make your own. Add ¾ teaspoon of fresh lemon juice or white vinegar to a measuring cup, then pour to the level of ¾ cup. Stir and allow to sit for 5 minutes before using.
Mixing the dough: once you add the buttermilk to the dry ingredients, stir only until the dry ingredients are just moistened to avoid over-mixing.
All nutritional values are approximate and provided to the reader as a courtesy. Changing ingredients and/or quantities will alter the estimated nutritional calculations.