• Preheat the oven to 350°F (180°C). Line a 12-hole muffin tin with paper liners. Spray cooking oil on the paper. Set aside.

Grate fruit and veggies

• Grate the zucchini (skin on) and squeeze them with your hands to discard any zucchini juice. Discard the juice and loosely pack the shredded zucchini in a measuring cup to measure the amount needed.
• Repeat the above steps for grated apples and grated carrots.
• Set aside the grated fruits and veggies in a bowl.

Muffin batter

• In a large bowl, whisk the dry ingredients: flour, sugar, cinnamon, baking powder, and baking soda. Set aside.
• In another large bowl, whisk the wet ingredients: egg, apple sauce, milk, avocado oil, and vanilla extract.
• Stir the dry ingredients into the wet.
• Fold in the grated fruits and vegetables halfway and any optional ingredients.
• Stir well to combine the muffin batter evenly.
• Divide the batter evenly into the 12 muffin holes.
• Bake in the center rack of the oven for 30 to 35 minutes or until golden brown on top and a pick inserted in the center of the muffins comes out slightly sticky. They are moist in the middle, so the stick won't come out dry.
• Cool completely on a cooling rack.

Storage

• Store in the fridge for 3-4 days in an airtight container or freeze for up to 1 month and thaw in the fridge before serving.