Preheat oven to 375°F degrees. Place muffin liners in muffin tin or spray tin with non-stick baking spray.
In a large bowl, whisk together flour, baking powder, salt, and cinnamon. Set aside.
In another large bowl, whisk together eggs and sugar until well blended. Add lemon zest and lemon juice and whisk until blended. Add milk, coconut oil, and vanilla and whisk until just blended.
Slowly add wet mixture to dry mixture in sections, gently folding the wet mixture into the dry mixture each time, until all of the dry flour mixture is completely blended. You'll end up with a thick, slightly lumpy batter. It's important not to overmix ingredients at this stage.
Then, gently add blueberries and fold into the mixture until somewhat evenly dispersed. Be very gentle here; it's easy to crush the blueberries.
Pour heaping tablespoons of batter into each muffin slot, filling just to the top. Sprinkle sanding sugar on top of each muffin if you wish. You can also sprinkle a mix of sanding sugar and cinnamon if you like more cinnamon flavor in your muffins.
Bake at 375°F degrees for 25-30 minutes, just until the tops of the muffins are lightly golden. Cool for 10 minutes before serving.
Notes
Measuring the coconut oil: the ½ cup measurement for coconut oil is the amount you should have of melted coconut oil.Storage: Keep in an airtight container at room temperature for up to five days. You can also freeze in an airtight container for up to three months.