Preheat oven to 180 degrees C. Spray 12 muffin cups with cooking oil spray.
Mix the flour, baking powder, bicarb soda and salt in a bowl.
In another bowl stir together the butter, egg, milk, zucchini and garlic until well blended. Mix the flour mixture into the milk mixture about 1/2 cup at a time, stirring between additions, until the flour mixture is incorporated.
Fold in the cheddar cheese, Parmesan cheese and diced bacon then pour the batter into the prepared muffin cups.
Cook in the preheated oven until a toothpick inserted into the centre of a muffin comes out clean; about 30 to 35 minutes. Allow muffins to cool slightly before removing from muffin cups; serve warm. Refrigerate leftovers.