In a Dutch oven, combine the blackberries, 1 cup sugar, 1/4 teaspoon salt and extract; bring to a boil. Reduce heat and simmer for 5 minutes. Meanwhile, in a bowl, combine flour, baking powder, nutmeg, remaining sugar and salt. Add milk; stir just until mixed (dough will be very thick).
Drop by tablespoonfuls into six mounds onto simmering blackberry mixture. Cover and simmer for 15 minutes or until a toothpick inserted into a dumpling comes out clean (do not lift cover while simmering). Spoon into serving dishes. Serve with cream or whipped cream if desired.