Blackberry Muffins

Name: Blackberry Muffins
Prep time: 20 min
Cook time: 20 min
Total time: 40 min
Cuisine: American
Ingredients: 2 1/2 cups (320g) all purpose flour; 1 tablespoon baking powder; 1/2 teaspoon baking soda; 1/2 teaspoon salt; 1/2 teaspoon cinnamon; 2 large eggs; 1 cup (236ml) sour cream; 1 teaspoon milk or water; 1 cup (200 g) sugar; 8 tablespoons warm melted butter (1 stick, 112 g); 1 teaspoon vanilla; 1 1/2 cups (about 5-6 oz, about 150g) of blackberries, fresh or frozen (if using fresh berries, cut them in half, if using frozen berries, defrost first, drain excess liquid, then coat them lightly in flour)