Don't beat those muffins! The baking soda and/or baking powder used to leaven muffins is activated by moisture (baking soda) and moisture/heat (double-acting baking powder). Once this reaction starts, there's no putting it on hold. You can stir your dry ingredients vigorously, and beat your wet ingredients to a froth, but when you put the two together, do it gently — you don't want to disturb those little air bubbles responsible for making your muffins rise.
Preheat your oven to 400°F. Grease and flour (or line with papers) a 12-well muffin pan.
Combine the flour, sugar, baking powder, salt and zest in a large bowl. Stir in the walnuts and raisins.
In a smaller bowl (or a two cup liquid measure), combine the eggs, milk and oil.
Make a well in the center of the dry ingredients and add the wet ingredients.
Stir just until barely combined and then gently fold in the zucchini.
Spoon the batter into the pan. Sprinkle with sparkling white sugar, for added crunch and flavor.
Bake for 20 to 25 minutes or until the muffins spring back when you press them with your fingertips.
Remove from oven and turn out onto a cooling rack. Serve warm or with a little butter.
Store, well-wrapped, for 3 days at room temperature. Freeze for up to a month.
