Preheat your oven to 350°F (175°C) and prepare a 9 x 5 inch loaf pan by spraying it generously with non-stick spray.

Grate the zucchini using a box grater or food processor. Gently squeeze the grated zucchini to remove excess moisture.

In a large mixing bowl, whisk together the all-purpose flour, baking powder, baking soda, and salt until well blended.

In a separate bowl, combine the milk and vinegar, allowing them to sit for a few minutes to curdle into buttermilk. Whisk in the melted butter and egg.

Pour the wet mixture into the bowl containing the dry ingredients and gently fold them together until just combined.

Add the squeezed zucchini, grated sharp cheddar cheese, and chopped green onions to the batter and fold until just incorporated.

Carefully pour the batter into your prepared loaf pan, smoothing the top.

Place the pan in the preheated oven and bake for approximately 1 hour until golden brown.

Remove the bread from the oven and let it cool in the pan for about 10 minutes, then transfer to a wire rack.