Preheat oven to 375°F. Line 17 muffin cups with paper liners and spray lightly with nonstick spray.
In a large bowl, combine flour and next 6 ingredients (through allspice). Make a well in the center of the mixture. In a small bowl, combine milk, butter, vanilla and egg; add to flour mixture, stirring until just moist. Gently stir in blackberries.
Spoon ¼ cup batter into each muffin cup. Sprinkle each lightly with sugar. Bake for 16 minutes, or until center springs back when touched. Cool in pans 10 minutes on wire racks.
Notes
You can use fresh blackberries, but place them in the freezer until they are frozen. Coarsely chop blackberries, then place them back into the freezer until ready to use. If they thaw too much, they will turn your muffins purple.