Pão de queijo are essentially a version of French gougères. Like gougères, the dough for pão de queijo starts on the stovetop and eggs are beaten in one at a time. Also like gougères, the end result is a tray of crispy, hollow puffs. The biggest difference is that pão de queijo are made with sour cassava flour or tapioca flour instead of all-purpose flour.
1 cup whole milk
1/2 cup vegetable oil
1 teaspoon salt
10 ounces tapioca flour or sour cassava flour (about 2 cups)
2 large eggs
1 to 1 1/2 cups grated Parmesan cheese
1. Heat the oven: Arrange 2 racks to divide the oven into thirds and heat to 450°F. Line 2 baking sheets with parchment paper or silicone baking mats.
2. Boil the milk and oil: Place the milk, oil, and salt in a medium saucepan and bring to a gentle boil over medium heat, stirring occasionally. Remove from heat as soon as you see big bubbles coming through the milk.
3. Add the tapioca flour: Add all of the tapioca flour and stir with a wooden spoon until you see no more dry tapioca flour. The dough will be grainy and gelatinous at this point.
4. Cool the dough: Transfer the dough to the bowl of a standing mixer fitted with a paddle attachment. (Alternatively, you can finish the dough by hand. Be prepared for a work-out.) Beat the dough for a few minutes at medium speed until it smooths out and has cooled enough that you can hold your finger against the dough for several seconds. There may be an oily slick that is not fully incorporated.
5. Beat in the eggs: With the mixer on medium speed, beat the eggs into the dough one at a time, waiting until the first egg is fully incorporated before adding the second. Scrape down the sides of the bowl as needed.
6. Beat in the cheese: Beat in the cheese on medium speed until fully incorporated. The resulting dough will be very sticky, stretchy, and soft with a consistency between cake batter and cookie dough. It will not be completely smooth.
7. Portion the puffs: Have a small bowl of water ready. For small puffs, scoop the dough by level tablespoons onto the baking sheets, spacing them about 1 1/2-inches apart (24 per baking sheet). For larger puffs, scoop the dough with a small (1 ounce or 2 tablespoon) ice cream scoop, spacing them about 2-inches apart (12 per baking sheet). Dip your scoop in water between scoops to prevent sticking.
8. Bake the puffs: Place the baking sheets in the oven and immediately reduce the heat to 350°F. Bake for 15 minutes. Rotate the baking sheets between racks and from front to back. Bake until the puffs have puffed, the outsides are dry, and they are just starting to turn golden-brown on the bottoms, 10 to 15 minutes more. (The tops will not brown much.) Cool for a few minutes and eat warm.