1. Preheat oven to 400 degrees Fahrenheit.
2. In a bowl, mix flour, sugar, baking powder, and salt.
3. In a separate bowl, mix oil, apple juice, eggs, and cinnamon.
4. Slowly mix wet mixture into dry mixture.
5. Wash frozen blueberries until the water runs almost clear, then dry them. Sprinkle with cornstarch to prevent them from sinking to the bottom of the muffins. Add to the batter but try to avoid mixing so they don’t turn the batter purple.
6. Scoop batter into individual cupcake holders, trying to get some blueberries in each scoop, filling holders almost until the top.