Prep the zucchini. Use a grater to shred the zucchini. Place the shredded zucchini in a clean kitchen towel and squeeze out as much moisture as possible. This step is key to preventing soggy bites.
Combine wet ingredients. In a large bowl, whisk together the liquid egg whites, milk, and vanilla extract. Whisk until the mixture is frothy.
Combine dry ingredients. In a separate bowl, mix the rolled oats, cinnamon, Splenda, baking powder, and salt.
Combine wet and dry. Add the dry ingredient mixture and the drained zucchini to the wet ingredients. Stir until just combined.
Rest the batter. Let the batter sit for 5 to 10 minutes. This gives the oats time to absorb some of the liquid, which improves the texture of the finished bites.
Preheat and prepare. While the batter rests, preheat your oven to 350°F (175°C). Grease a standard 12-cup muffin tin with non-stick cooking spray.
Bake. Pour the batter evenly into the prepared muffin tin, filling each cup about three-quarters of the way. Bake for 20 to 25 minutes, or until the bites are set and a toothpick inserted into the center comes out clean.
Cool and serve. Let the bites cool in the pan for a few minutes before moving them to a wire rack to cool completely. Enjoy them warm or save them for a convenient grab-and-go snack.