Preheat the oven to 425°F. Line two 12-cup muffin tins with cupcake liners (this recipe makes 14-15 muffins).
In a large bowl, whisk together the flour, baking powder, salt, cinnamon, sugar, and all spice.
In a separate large bowl, whisk together the sugar, vegetable oil, and vanilla.
Add the dry ingredients to the wet ingredients and mix together with a wooden spoon or spatula just until incorporated.
Fold the applesauce and grated zucchini into the batter until fully incorporated.
Use a cookie, ice cream scoop, or spoon to scoop batter into each lined muffin cup, filling about ¾ of the way full.
Bake at 425°F for 5 minutes, then lower the heat to 375°F and bake for an additional 15 minutes.
Allow the muffins to cool in the muffin tin for 5 minutes before transferring to a wire rack to continue cooling.
Notes
Makes 14 muffins.Storage: Allow the muffins to cool then store in an airtight container for up to one week. Freeze: Freeze in a freezer bag or freezer-safe container for up to two months.