I love the look of this rustic gratin. I serve it right off of the browned parchment paper. You can easily make it in a 9x13-inch baking dish or your favorite gratin dish.
Kosher salt and freshly ground black pepper for each of the layers
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2Yukon Gold potatoes -- sliced crosswise into 1/8-inch slices
1medium-sizedred onion peeled and sliced into paper thin slices
1medium-sizedgarnet yam peeled and sliced crosswise into 1/8-inch slices - microwave the slices in a covered dish with 2 tablespoons of water for 4 minutes
1largeyellow summer squash sliced crosswise into 1/8-inch slices
1zucchini sliced crosswise into 1/8-inch slices
1cuproughly chopped fresh basil leaves
2large tomatoes stem end removed; sliced crosswise into 1/4-inch slices
Instructions
Preheat the oven to 350ºF. Line a baking sheet with parchment paper and brush it with olive oil.
Combine the panko, cheese, thyme, sea salt, and black pepper in a small bowl and set aside.
Arrange the potato slices in a 9x13" rectangle on the oiled parchment; sprinkle lightly with salt and pepper and 1/3 cup of the panko mixture.
Arrange the onion evenly on top of the potatoes; sprinkle lightly with salt and pepper and 1/3 cup of the panko mixture. Repeat the process with the yams, yellow squash, and zucchini.
Arrange the chopped basil leaves over the entire top.
Arrange the tomatoes, overlapping, on top of stacked vegetables; cover with parchment paper and press lightly to even and join the layers.
Cover the entire pan with aluminum foil. Bake for 1 hour; the vegetables will not be cooked through.
Remove the pan from the oven. Remove the foil and top parchment paper. Sprinkle the top of the gratin evenly with the remaining panko mixture. Return the pan to the oven for 20 minutes. Vegetables should be cooked through and the top of gratin will have browned.
Remove the gratin from the oven and cool for 20 minutes before serving.