Pillowy-soft, cheesy zucchini muffins infused with garlic butter, scallions, sharp cheddar, and Parmesan for a deeply savory, tender crumb. A quick one-bowl bake that’s moist without squeezing the zucchini, ideal warm with a pat of butter and flaky salt.
Preheat oven to 425°F (220°C). Line a 12-cup muffin pan with non-stick liners or lightly spray with oil.
In a large heat-safe bowl, combine the butter and minced garlic. Microwave on low power in 20-second intervals, stirring between each, until the butter is melted.
Whisk in eggs, milk, fine sea salt, and black pepper until smooth. Stir in the shredded zucchini and minced scallions until evenly combined.
Add the all-purpose flour and baking powder; stir until the flour is halfway incorporated. Add the shredded cheddar and grated Parmesan, then stir just until the batter is combined (it will be thick).
Divide batter among 12 muffin cups (about 1/4 cup each, mounded). Bake 5 minutes at 425°F, then without removing the pan, reduce oven to 350°F (177°C) and continue baking until golden and a toothpick comes out clean, about 20 minutes more. Cool 10 minutes in the pan, then transfer to a rack to cool completely.