Set the oven to 425°F (218°C) and prepare a 12-cup muffin pan with grease or liners. This recipe makes about 10 muffins, so plan your pans accordingly.
Whisk together flour, baking powder, baking soda, salt, cinnamon, and nutmeg in a large bowl.
In a separate bowl, combine oil, brown sugar, granulated sugar, vanilla, and an egg. Stir in the grated zucchini for a moist, fluffy texture—no need to wring it out.
Gently fold the wet ingredients into the dry mixture until just combined. Avoid over-mixing to keep your muffins light and tender.
Beat softened cream cheese until smooth, then mix in an egg yolk, vanilla, and sugar for a creamy, slightly sweet filling.
Layer each muffin cup with batter, cream cheese filling, and more batter to fill the cups. Let the filling peek out to add charm, and sprinkle coarse sugar on top for sparkle.
Bake at 425°F (218°C) for 5 minutes, then reduce to 350°F (177°C) and bake another 15-17 minutes. The high heat ensures bakery-style domed tops and a perfect golden finish.
Let muffins cool in the pan for 10 minutes before transferring to a wire rack. Enjoy!