Preheat the oven to 180°C (350°F). Line a 12-cup muffin pan with paper liners.

Add all the dry ingredients to a large mixing bowl and mix until there are no more lumps. Add all the wet ingredients (including the zucchini) and mix until just combined. If you're using nuts or chocolate chips, add them at the same time as the wet ingredients.

Use an ice cream scoop or a spoon to divide the batter into your muffin pan. The muffin batter should be close to the top of each cup (check the step-by-step images above, note 3).

Using the same bowl, add all ingredients for your crumb topping. Mix with a spoon or your fingertips until combined and the mixture is flaky and crumbly.

Generously sprinkle the crumb topping onto your muffins.

Bake the muffins for 23-28 minutes or until you can insert a toothpick in a muffin and it comes out clean. These muffins are very moist so a few crumbs on your toothpick are fine.

Allow the muffins to cool in the muffin pan for 15 minutes (or until they aren't too hot) then place them on a wire rack.

Enjoy the vegan zucchini muffins warm or at room temperature. They're perfect by themselves or with some vegan butter.

Store any leftover muffins in an airtight container at room temperature for up to 3 days, in the fridge for up to 5 days or in the freezer for up to 1 month. If the crumb topping softens over time, you can reheat them in the oven for 10 minutes at 160°C (320°F) or until heated through.