Tuscan Zucchini Scarpaccia: The Crispy Summer Tart Step-by-step instructions

Before you start

Before starting, ensure all your ingredients are measured and your workspace is clean. Use a mandoline to slice the zucchini and onions, as uniform thickness is critical for the tart to bake evenly. If you do not have a mandoline, use a sharp chef's knife and take your time to ensure the slices are as thin as possible.

Preheat your oven well in advance to 425°F (220°C) to ensure it reaches the necessary temperature before the tart goes in. Have your baking sheet and olive oil ready to go, and clear enough counter space to accommodate the large pan.

Instructions

Slicing and Salting

1. 1Slice and Salt
   Using a mandoline, slice the zucchini and white onion into paper-thin 1mm coins. Place the slices in a colander and toss thoroughly with kosher salt. Let the mixture sit for at least 20 minutes to draw out approximately 60ml of natural liquid. Do not discard this liquid, as it is essential for the structure and flavor of the batter.
   Look for The zucchini slices should look limp and release a significant amount of water into the bowl.
   Tip Ensure the slices are truly uniform to guarantee consistent crisping across the entire baking sheet.

The zucchini and onion slices should be uniform, and the salt should have drawn out enough liquid to create a noticeable pool in your colander. The vegetables should look slightly translucent and limp, signaling they are ready to be used in the batter. If the mixture is still very dry, let it sit for an additional five minutes before proceeding.

Mixing the Batter

2. 2Prepare the Batter
   In a large mixing bowl, combine the reserved zucchini liquid with the all-purpose flour, fine cornmeal, and grated Parmigiano-Reggiano. Whisk the ingredients vigorously until a smooth, thin batter forms. If the batter appears too thick, add a tablespoon of water, but maintain a consistency that is easy to spread across the pan.
   Look for The batter should be thin enough to pour but thick enough to coat the back of a spoon.
   Tip Whisking thoroughly prevents clumps of flour from forming in the finished tart.

The batter should be smooth, thin, and well-combined with no flour pockets. It should have the consistency of a thin, pourable crepe batter.

If the mixture feels too thick, adjust with a tiny amount of water. Ensure the Parmesan is evenly incorporated so that every square of the final tart will have a consistent, savory flavor profile throughout.

Baking and Garnish

3. 3Bake to Perfection
   Preheat your oven to 425°F (220°C). Generously coat a large baking sheet with olive oil. Pour the batter mixture onto the sheet, using a spatula to spread it into an ultra-thin 4mm layer. Bake in the center of the oven for 30 minutes until the edges are dark golden-brown and blistered. Remove from the oven, garnish with zucchini blossoms, fresh basil, and flaky salt before slicing into squares with a pizza wheel.
   Look for The edges should be dark golden-brown and crispy, and the center should be set and firm to the touch.
   Tip For the best result, use a high-quality olive oil to coat the pan, as it will help fry the bottom of the tart.

The tart should be golden-brown with dark, crispy edges. The surface should look dry and lacy. Before adding the garnishes, ensure the tart is not sticking to the pan. If you see any soft spots, return it to the oven for a few more minutes. The final dish should be firm and easy to slice into clean, crisp squares with your pizza wheel.

Common mistakes

A common mistake is slicing the zucchini too thick, which prevents the tart from crisping up properly and leads to a soggy, uneven result. Another error is failing to salt the zucchini long enough; the moisture removal is crucial for the batter's consistency and final texture.

Finally, do not overcrowd the baking sheet. If the layer is thicker than 4mm, the center will struggle to bake through, resulting in a dense, chewy tart rather than the delicate, crispy wafer that makes Scarpaccia so unique and enjoyable.

How to tell it’s done

The tart is ready when the edges are visibly dark golden-brown and blistered, indicating a deep, crispy texture. The surface should look lacy and firm, with no signs of wet or doughy batter remaining in the center.

Use a spatula to gently press the middle; it should feel set. When you slice into it with a pizza wheel, it should produce a distinct, audible crackle, confirming that the crust has achieved the desired crispness throughout the entire sheet.