Lazy Summer Tian

In a medium nonstick skillet (preferably 10 inches across the top and 9 inches across the base), heat the 2 tablespoons olive oil over medium heat. Add the onion, season with salt and pepper and cook, stirring occasionally, until the onions are soft and about half-browned all over, 15 to 17 minutes. Add the chile, if using, and cook for 2 minutes.

While the onions and chile cook, cut the ear of corn in half crosswise. Place a box grater in a bowl and use the large holes of the grater to grate the corn off the cob; you should have lots of the corn “milk” as well. Add the corn and its liquid to the skillet with the onions and chile and cook just until the liquid mostly evaporates, about 1 minute. Remove the skillet from the heat and scrape the onion-corn mixture into a bowl; let cool.

Rinse the skillet (this also helps it cool down), then wipe it clean and dry with a paper towel. Return the skillet to the stove over low heat, and add the butter. While the butter melts, slice the potatoes using a mandoline to make them all 1/8-inch thick; slightly thinner is fine but not thicker. Begin placing slices of potatoes on the bottom of the skillet, starting from the outside and spiraling your way to the center, overlapping each slice on the previous slice by about 1/4 inch. Once one layer of potatoes is complete, season it lightly with salt and pepper, then arrange more potato slices to make a second layer; season again with salt and pepper. Cover with a lid and let cook for 2 minutes.

Uncover the skillet and spoon half of the onion-corn mixture evenly over the potatoes, then use the back of the spoon to gently spread it over the potatoes in a thin coating; be as gentle as possible so as not to disturb the layers of potatoes. Cover the skillet and cook for 2 minutes.

Meanwhile, slice the zucchini and squash on the mandoline in the same way. Uncover the skillet and create a layer of zucchini and squash (you can do just zucchini or an alternating mix of both). Season the layer of zucchini with salt and pepper, then drizzle lightly with more olive oil so the slices are evenly dressed. Cover and cook for 2 minutes. Heat the oven to 375 degrees F.

Uncover the skillet and arrange a single layer of potatoes over the zucchini. Season with salt and pepper and drizzle with olive oil like before. Cover and cook for 2 minutes. Uncover the skillet and spoon the remaining onion-corn mixture over the potatoes, taking care to spread it out gently, then cover and cook for 2 minutes. Uncover the skillet and arrange another layer of zucchini and squash; season with salt and pepper and drizzle with more olive oil. Cover and cook for 2 minutes.

While the final layer cooks, very thinly shave the garlic cloves, then place in a bowl with the halved tomatoes. Season with salt and pepper and toss to combine. Uncover the skillet and scrape the tomatoes and garlic over the squash slices, then use your (clean) bare hands to gently spread them out and lightly press down on them to ensure the tian is even (remember the skillet is hot and be aware of your fingertips). Pour the wine slowly and evenly over the vegetables.

Spread the breadcrumbs evenly over the tomatoes, then season with a final pinch of salt and pepper and drizzle evenly with olive oil. Transfer the skillet to the oven and bake until all the vegetables are tender and the breadcrumbs on top are golden brown and crisp, 40 to 45 minutes.

Remove the skillet from the oven and let it stand until completely cooled or at least barely warm, about 1 hour but preferably for 2 hours; this allows the vegetables time to collapse together and marry their flavors. Serve at room temperature with chilled glasses of rosé or white wine or light beer.