In a large mixing bowl, whisk together the all-purpose flour, granulated sugar, baking powder, baking soda, salt, ground cinnamon, and powdered milk until well combined.
Gently fold in the dried blueberries to evenly distribute them throughout the dry mixture.
Transfer the muffin mix to an airtight container or resealable bag for storage.
To prepare muffins from the mix: Preheat oven to 375°F (190°C). In a separate bowl, combine 1 cup of the muffin mix with 1/3 cup vegetable oil, 1 large egg, and 1/3 cup milk. Stir until just combined.
Spoon batter into a greased or lined 12-cup muffin tin, filling each cup about 2/3 full.
Bake for 18-22 minutes or until a toothpick inserted in the center comes out clean.
Allow muffins to cool in the pan for 5 minutes before transferring to a wire rack to cool completely.