Preheat the oven to 350°F. Line a 12 cup muffin tin with paper liners.
In a large mixing bowl, whisk together the flour, baking powder, baking soda, salt, and cinnamon.
In a medium mixing bowl, whisk together the eggs, oil, sugars, and vanilla until lightened in color and smooth.
Add the wet mixture and zucchini to the dry mixture and gently stir until combined and no dry streaks of flour remain. (The batter will be thick. The zucchini will continue to release moisture as the muffins bake.)
Use a triggered ice cream scooper to fill the muffin liners almost all of the way full. Bake for 24 to 26 minutes or until a toothpick inserted into the center of the muffins comes out clean.
Let the muffins cool for 5 minutes in the pan, then transfer them to a wire cooling rack to cool completely.
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Notes
Use room temperature ingredients. Set the eggs out 30 minutes or so before you start baking so they can warm up to room temperature. This will make it easier to incorporate with the other ingredients.
Weigh the flour. Using too much flour in these muffins will make them dry and crumbly instead of soft and moist. The best way to measure flour is by weighing it with a kitchen scale. If you don't have one, fluff the flour in its canister and spoon it into your measuring cup. Use a knife to level off the top. Do not scoop directly from the container.
Don't over-mix the batter. Your muffins will turn out dense and hard if you stir them excessively. Just mix until the flour is fully incorporated.
Do not wring the zucchini dry or squeeze out any liquid before adding to the wet ingredients. It provides moisture to the muffins while baking. If you lose this excess moisture, the muffins will be dense, dry, and not very delicious.