Preheat oven to 400 degrees. Spray nonstick or silicone muffin pan with oil, as these can stick.
Mix all wet ingredients (oil, egg, and milk) in a large bowl. You can use a whisk or spoon to mix by hand.
Add the tapioca flour slowly and mix into the wet ingredients. The resulting mixture will be a thick liquid batter.
Grate the parmesan and cheddar cheese and add to the liquid base. Add salt. Mix in lightly, cheese should still be visible and not disintegrate.
Using a spoon or ladle, carefully pour batter into each muffin cup. Can fill each cup about 3/4 or more. If any batter is left over, top off. Add topping (garlic powder is my favorite) if using.
Bake for 15 minutes. Remove from oven and cool for 5 minutes. Enjoy immediately, the sooner the better.