Place liners in cups of a standard 12-cup muffin tin.*
Stir together the flours, sugars, baking powder, soda, salt, and cinnamon in a large bowl.
In a smaller bowl (a 2-cup measure with pour spout is perfect), mix the yogurt, butter, and egg. Add to the flour mixture, along with the zucchini and stir just until mixed.
Spoon the batter into the prepared muffin tin. Sprinkle with sugar, if desired. Freeze for about 30 minutes until firm and then transfer the individual cups to freezer bags or containers, label and freeze until ready to bake (or bake immediately - see note**).
When ready to bake, preheat oven to 375 degrees and place as many frozen muffins as you want back into a muffin tin (to keep their shape). Bake for about 30 minutes, or until a toothpick in the center comes out clean. Remove baked muffins from the tin and transfer to a baking rack to cool.***
*This recipe really makes more than 12- you can get two or three more from one batch and 6 more from a double batch. Just freeze the extra in lined cups or small ramekins if you don't have more muffin tins.**You can bake them right away, as well: Bake at 375 for 20 minutes.***They tend to stick to the paper wrapper after being frozen and baked - you can let them cool fully or use easy-release muffin liners.Variations (add all to batter before freezing):
1/2 cup of chocolate chips
1/2 cup of dried fruit like cranberries or blueberries