"The recently published Beekman 1802 Heirloom Vegetable Cookbook is filled with wonderful recipes that highlight the flavors of all types of heirloom vegetables. In the book, this vegetable gratin recipe is prepared with heirloom vegetables, but any combination of tomatoes, peppers and squash will work as well...."
INGREDIENTS
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3 tablespoons extra-virgin olive oil (divided)
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1 medium red onion, peeled and finely chopped
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2 garlic cloves, peeled and finely chopped
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2 medium yellow squash or zucchini cut into  1/4-inch round slices
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1 red bell pepper, seeded and cut into  1/2-inch pieces
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 3/4 teaspoon salt (divided)
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 1/4 cup fresh basil or oregano leaves, coarsely chopped
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 1/2 cup plus 2 tablespoons grated Parmesan cheese (divided)
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1 pound tomatoes (see note)
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 1/2 cup fresh breadcrumbs or panko crumbs