In a small saucepan over medium heat, combine the milk, butter, and salt. Bring just to a simmer so the butter melts and the mixture is hot but not boiling (bubbles around edge). Remove from heat immediately.

Mix with tapioca flour

Place the tapioca flour in a large heatproof bowl. Pour the hot milk-butter mixture over the flour and stir vigorously with a wooden spoon until a smooth, slightly sticky paste forms and there are no dry streaks (about 1 minute). Let cool 5 minutes so it’s not too hot for the eggs.

Incorporate eggs and cheeses

Add the eggs one at a time, mixing thoroughly after each addition until fully incorporated and the dough becomes glossy and elastic. Stir in the grated Parmesan and grated mozzarella until evenly distributed. The dough should be soft and slightly sticky; if too loose, add up to 2 tbs more tapioca flour, 1 tbs at a time.

Add zaatar

Fold in the zaatar until evenly distributed through the dough, reserving a small pinch for sprinkling on top if desired.

Shape the balls

Wet your hands lightly or oil them with a little olive oil. Using a tablespoon or small cookie scoop (about 1 to 1 1/4 tablespoons), portion the dough and roll into smooth balls about 1 to 1 1/4 inches (2.5–3 cm) in diameter. Place balls on the prepared baking sheet spaced about 1 inch apart. If dough sticks, dip hands in water or oil between rolls.

Brush and sprinkle

Brush each ball lightly with olive oil and sprinkle the reserved pinch of zaatar on top for visual flavor contrast.

Bake

Bake in the preheated oven for 15–20 minutes, or until the exterior is puffed and lightly golden. Pão de queijo will be hollow-ish inside and have a chewy, cheesy interior. For extra browning, broil 1–2 minutes—watch carefully to avoid burning.

Finish

Remove from oven and let cool 3–5 minutes on the tray. Serve warm so they are gooey inside.

Harissa & Tomato Dipping Sauce

Prepare tomato

If using fresh tomato: blanch (optional) by scoring an X on the bottom, dropping into boiling water 20–30 seconds, then into an ice bath; peel, core, and finely chop. If using canned diced tomato, drain excess liquid and chop finely if large.

Combine ingredients

In a small bowl, mix the chopped tomato, harissa paste, minced garlic, extra-virgin olive oil, lemon juice, honey (or sugar), salt, and black pepper. Stir until well combined. Taste and adjust seasoning or harissa level to your heat preference.

Rest and finish

Let the sauce sit at room temperature for at least 10 minutes to allow flavors to meld. Stir in the chopped parsley or cilantro just before serving for freshness.

Serve

Transfer the sauce to a small serving bowl alongside the warm zaatar pão de queijo for dipping.