Combine flour and next 6 ingredients (flour through salt).
In a separate bowl, whisk together egg, butter, and milk. Add to flour mixture, and whisk to combine. Stir in zucchini.
Spray griddle with cooking spray and heat on medium. Spoon batter onto griddle (about ¼-cup per pancake) and cook until tiny bubbles appear in the pancake. Flip and continue cooking until golden on both sides. Serve with maple syrup and blueberries.
Notes
Makes about 20 pancakes.Make ahead tip: Grate zucchini the night before and store in the refrigerator in a sealed container.