Step 1

Preheat oven to 350°F. Grease a 12-count muffin pan with nonstick spray or line with cupcake liners. Grease the top of the pan to keep the muffin tops from sticking.

Step 2

Whisk together the flour, baking powder, baking soda, cinnamon, and salt in a small bowl. Set aside.

Step 3

In a large bowl, whisk together the brown sugar, eggs, oil, and vanilla extract. Mix until smooth. Add the shredded zucchini. Mix to combine. Add the flour-mixture. Mix until a batter forms. Stir in nuts, dried fruit, or chocolate if using.

Step 4

Allow batter to rest for five minutes while you prepare the crumb topping.

Step 5

Stir together the flour, oats, cinnamon, and salt. Add the brown sugar. Break up any lumps with a fork or your fingers. Add melted butter and stir until combined.

Step 6

Spoon batter into prepared muffin cups, filling them about ⅔ full. Sprinkle crumb topping, about two teaspoons each, onto each muffin.

Step 7

Bake for about 25 minutes or until a toothpick inserted in the center comes out clean.

Step 8

Allow the muffins to cool for 5 minutes in the muffin pan, and then transfer to a wire rack to cool completely.

Step 9

Cover and store at room temperature for up to three days. To freeze: let muffins cool and place them in a freezer container. Freeze up to two months.