Preheat your oven to 350°F (175°C). Grease a 9×5-inch loaf pan or line it with parchment paper.

Grate zucchini using a coarse grater. No need to peel. Lightly blot with a paper towel if overly wet, but don’t squeeze out all moisture.

In a large bowl, whisk together eggs, melted butter, vegetable oil, vanilla extract, and granulated sugar until smooth.

Stir in the cake mix and ground cinnamon until fully incorporated. Gently fold in the shredded zucchini with a spatula.

Stir in any optional mix ins like chocolate chips, peanut butter chips, or nuts. Pour the batter into the prepared loaf pan.

For loaf: Bake for 50–60 minutes or until a toothpick inserted into the center comes out clean. Let cool in the pan for 10–15 minutes, then transfer to a wire rack to cool completely. Slice and serve!