Preheat oven to 350
Prepare muffin tins with a non-stick spray, oil, silicone liners, or paper cupcake holders.
In a small bowl add flour, cinnamon, baking soda, baking powder, salt, and walnuts. Mix. Set aside.
In a large mixing bowl add eggs, oil, vanilla, and sugar. Mix well.
Add zucchini and mix well.
Add flour mixture and stir to mix. Don’t over-mix; this will make your muffins tough.
Fold in blueberries.
Spoon into muffin tins about 3/4 full
Bake muffins for 25 minutes. Check a few minutes early in case of oven variations.
Let muffins sit for no more than 5 minutes before removing them from the muffin pan, as this helps them hold their shape and prevents your muffins from becoming soggy on the bottom.
Let muffins cool completely on wire racks.