Preheat the oven to 375°F (190°C) and line muffin tins with paper liners.

In a large bowl, mix together all-purpose flour, granulated sugar, baking powder, baking soda, ground cinnamon, ground nutmeg, and salt.

In another bowl, whisk eggs, vegetable oil, and vanilla extract. Fold in grated zucchini.

Combine the wet mixture into the dry mixture and fold gently to mix.

Fill muffin tins two-thirds full with batter and add optional crumb topping if desired.

Bake in the preheated oven for 20-22 minutes. Check doneness with a toothpick.

Let cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.