Preheat oven to 375 degrees F (190 degrees C). Grease a 9x13 inch baking dish.
In a small bowl, mix together the sugar, cornstarch, cinnamon, and nutmeg. Add the blackberries and rum, and toss to coat.
Spread the blackberry mixture into the prepared baking dish. Dot with butter.
In a medium bowl, stir together the flour, baking powder, and salt. Cut in butter until the mixture resembles coarse crumbs. Stir in the milk just until moistened.
Drop spoonfuls of the batter over the blackberry mixture. Bake in preheated oven for 25 minutes, or until the top is golden brown.
Interesting Facts:
The term “cobbler” was first used in the 16th century, and is thought to have originated from the English word “cobeler”, meaning “wooden bowl”.
Rum has been made since the 17th century and was originally made from sugarcane.
Blackberries are a member of the rose family and are native to North America.