Preheat your oven to 425°F and grease a standard 12-cup muffin pan with butter or cooking spray. While the oven heats, whisk together the flour, baking powder, fine sea salt, black pepper, dry mustard powder, and red pepper flakes in a large bowl. Set this dry mixture aside—this is your foundation for a perfectly textured muffin with balanced seasoning throughout.

Melt the butter in a large mixing bowl (you can microwave it for 30-45 seconds or use a small saucepan). Add the minced garlic to the warm butter and let it sit for about 1 minute to gently soften and infuse—this blooming technique releases the garlic's flavor without making it harsh or bitter. This aromatic base will give your muffins real depth.

Whisk the eggs and milk directly into the garlic-butter mixture until well combined. Fold in the squeezed zucchini (make sure you've really wrung out that excess moisture—it prevents dense, soggy muffins) and minced scallions. This is where your vegetables are distributed evenly, ensuring every muffin has that fresh, savory element.

Pour the wet mixture into the bowl with the dry ingredient mixture from Step 1. Using a spatula or wooden spoon, gently fold the two together—stop when you still see a few streaks of flour. I like to leave the batter slightly undermixed at this point because overmixing develops gluten and creates tough, dense muffins instead of tender ones.

Gently fold the shredded sharp cheddar and grated parmesan cheese into the batter from Step 4 until just combined—the streaks of flour should now be mostly incorporated, but don't overstir. The cheese adds moisture and richness, so you want it distributed evenly without overdeveloping the gluten.

Divide the batter evenly among the 12 prepared muffin cups, filling each about three-quarters full. Bake at 425°F for 5 minutes to set the structure, then reduce the oven temperature to 350°F and bake for an additional 20 minutes, or until a toothpick inserted into the center comes out with just a few moist crumbs. The initial high heat sets the muffin structure, while the lower temperature allows them to cook through without browning too much.

Remove the muffin pan from the oven and let the muffins cool in the pan for 10 minutes. This resting time allows the structure to set so they won't fall apart when you remove them. After 10 minutes, run a thin knife around the edges and turn them out onto a wire rack to cool completely, or serve them warm with butter.