Preheat oven to 350°F. and line a 12-cavity muffin tin with parchment paper liners or silicone liners.
Grate the zucchini and let it stand to drain.
Melt the butter and set it aside to cool.
Chop the green onions (scallions) and grate the cheese.
In a medium bowl, whisk the dry ingredients together.
In a large bowl, combine the eggs, buttermilk, and melted and cooled butter.
Add the dry ingredients to the wet ingredients and stir until combined.
Stir in the green onions (scallions) and grated cheese.
Squeeze as much water as you can from the grated zucchini, using a clean teatowel or cheesecloth. Gently fold it in to the muffin batter.
Divide the batter among 12 muffin tins.
Bake at 350°F. for 20 - 22 minutes or until a toothpick inserted comes out clean or with just a few crumbs.
Let sit in the muffin tin for 10 minutes, then remove to a wire rack to cool.
Make your own buttermilk substitute by adding ¾ tablespoon lemon juice or vinegar to ¾ cup of milk.Use parchment paper muffin liners or silicone muffin cups to bake these zucchini cheddar muffins. The cheese will stick to regular white paper muffin cups making the muffins difficult to remove.Reserve ¼ cup of the grated cheese to add to the top of the muffins before baking.