Preheat oven to 350 degrees and spray a 9 x 5 bread pan with non-stick spray.

Wrap grated zucchini in a paper towel and squeeze until some of the liquid releases. You don't need to completely dry it out, just a tablespoon of liquid or so.

In a large bowl, combine flour, baking powder, baking soda and salt.

In a small bowl, combine milk and vinegar. The milk will curdle a bit. (you just made homemade buttermilk!) Mix in melted butter and egg.

Add milk mixture to dry mixture being careful not to over mix. (over mixing will make for a low rising bread).

Add grated zucchini, cheese and onions. Mixing lightly until just combined.

Pour batter into prepared pan and bake at 350 degrees for one hour.

If toothpick inserted comes out clean, bread is done! Cool for 10 minutes in the pan. Remove carefully and cool on wire rack.