Cornmeal gives this rustic cobbler a satisfying texture. Serve with whipped cream or vanilla ice cream -- both pair nicely with the sweet-tart huckleberries.
Heat oven to 350 degrees. Melt butter in a 10-inch cast-iron skillet in oven, about 5 minutes.
Meanwhile, toss huckleberries with 2 tablespoons sugar in a medium bowl. Whisk together flour, cornmeal, baking powder, salt, and remaining 1 cup sugar in a large bowl. Add milk and vanilla. Remove skillet from oven and add melted butter to flour mixture; whisk until just combined. Pour batter into skillet; top with huckleberries and juices.
Bake until golden brown and fruit is bubbling, 40 to 45 minutes. Let stand 10 minutes before serving.
If you can't find frozen huckleberries, substitute frozen wild blueberries. This cobbler can also be baked in a 10-inch pie dish.