Heat 3/4 cup of milk and 1/3 cup of vegetable oil in a saucepan. Bring to almost boiling point - just until you see the first bubbles appear. Turn off heat immediately.

Add 1 1/3 cups of tapioca flour mixed with 1/2 teaspoon of salt to the hot milk mixture. With heat turned off, mix until well incorporated. The mixture will look weird and lumpy - this is normal!

Let the mixture cool for about 5 minutes. Add 1 large egg on top of the mixture and mix well with a rubber spatula or your hands until everything is well incorporated. You can't overmix this batter since it's gluten-free.

Mix in 40g of grated Parmesan cheese and 80g of grated mozzarella cheese until evenly distributed throughout the batter.

Preheat oven to 400°F (200°C). Line a baking pan with parchment paper. Oil your hands lightly with vegetable oil and shape the dough into 12 balls, making them as big or small as you prefer. Place on the prepared baking sheet.

Bake for 18-20 minutes at 400°F until golden brown and puffed. Optionally, top with extra Parmesan cheese before serving.