Preheat oven to 375 degrees F. Line 12 to 14 2-1/2-inch muffin cups with paper bake cups; set aside. In a medium bowl stir together the flour, baking powder, and salt; set aside.
In a large mixing bowl beat butter and the 2/3 cup granulated sugar until lightly and fluffy, scraping sides of bowl. Add eggs 1 at a time, beating well after each addition. Alternately add flour mixture and milk to butter mixture, stirring after each addition just until combined. Fold in huckleberries or blueberries.
Spoon batter into prepared muffin cups, filling each just over three-fourths full. If desired, sprinkle tops with sugar. Bake about 20 minutes or until muffins are golden brown and a wooden toothpick inserted near centers comes out clean.
Cool muffins in pan on a wire rack for 5 minutes. Remove from muffin cups; let cool about 15 minutes before serving. Makes 12 to 14 muffins.