In a large bowl gather flour, salt, baking soda, baking powder, and cinnamon (if using) and gently mix.
Measure oil into a blender, then fill with chunks of zucchini until 3 cups. Blend until free of chunks, but not too long.
Beat eggs in a medium bowl until foamy. Add sugar and vanilla, mix well.
Add egg mixture and zucchini mixture to dry ingredients. Mix until smooth.
Bread Loaf
Grease one large loaf pan and pour in batter. Bake for an hour, or until an inserted toothpick comes out clean.
Muffins
Grease 24 muffin cups or use paper cups. Fill each cup 3/4 full. Bake for 25 minutes.
Mini Muffins
Grease mini muffin cups or use paper cups. Fill each cup 1/2 full. Bake for 16 minutes.
Notes
Lately I've been mixing up the recipe without cinnamon, baking 12 muffins, then mixing in 1/2 tablespoon cinnamon to the remaining batter and baking the other 12. Everyone in our family is happy that way!