Step 1

Preheat oven to 550°F and set a well-seasoned cast iron skillet inside to preheat.

Step 2

Meanwhile, combine flour, salt, and baking powder in a large mixing bowl. Slowly add water, whisking constantly, to form a smooth crêpe-like batter. Whisk vigorously for 1 minute to help aerate batter. Let rest 20 minutes.

Step 3

Remove skillet from oven and grease with vegetable oil. Add enough batter to skillet, swirling, to cover entire bottom surface in a thin, even layer. Set over high heat and cook until browned and crisp on the bottom, about 3 minutes.

Step 4

Using a thin metal spatula, lift pancake and flip. Cook on other side until browned in spots, about 1 minute. Transfer pancake to a rack or clean paper towel to cool. Wipe skillet clean, grease, and repeat with remaining batter. Try not to stack pancakes once done: You want them to dry, not steam.

Step 5

Cut pancakes into roughly 2-inch diamond shapes. Bring a pot of salted water to a boil, then remove from heat. Add pancake pieces until all are submerged, then drain in a colander right away.

Step 6

Transfer pancakes to a large, clean mixing bowl and toss gently with pesto. Spoon testaroli on plates, top with basil leaves and more grated cheese and serve.