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1
If you have a food mill, quarter tomatoes.
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2
If not, peel, seed and chop them.
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3
(See step 5.)
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4
To make tomato sauce, heat 1 tablespoon olive oil in a large, heavy skillet over medium heat and add onion.
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5
Cook, stirring often, until tender, about 5 minutes.
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6
Add garlic.
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7
Cook, stirring, until fragrant, 30 seconds to a minute, and add tomatoes, salt, pepper, sugar and basil sprigs.
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8
Increase heat to medium-high.
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9
When tomatoes are bubbling briskly, stir and reduce heat to medium.
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10
Cook, stirring often, until tomatoes have cooked down and are beginning to stick to pan, 15 to 25 minutes, depending on consistency.
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11
Remove basil sprigs; taste and adjust seasoning.
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12
Heat oven to 450 degrees.
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13
Line 2 sheet pans with parchment.
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14
Trim ends off zucchini and cut in half crosswise, then into lengthwise slices, about 1/4 to 1/3 inch thick.
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15
Season on both sides with salt and pepper and toss with 2 tablespoons olive oil.
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16
Arrange zucchini slices on baking sheets in one layer and sprinkle with red pepper flakes.
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17
Roast for 12 minutes, until lightly browned and easily pierced with a knife.
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18
Remove from oven and reduce heat to 375 degrees.
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19
If using a food mill, put sauce through medium blade.
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20
If not, pulse sauce in a food processor fitted with steel blade until just coarsely pureed.
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21
Stir in chopped basil.
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22
To assemble the dish, oil a 2-quart gratin with olive oil.
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23
Spread 1/4 cup tomato sauce over bottom of dish.
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24
Arrange a third of the zucchini in an even layer over tomato sauce.
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25
Spoon a third of remaining sauce over zucchini and sprinkle with 1/4 cup Parmesan.
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26
Repeat with 2 more layers, ending with 1/4 cup Parmesan.
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27
Drizzle on remaining tablespoon olive oil.
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28
Bake 30 to 35 minutes, until bubbling and browned on the top and edges.
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29
Remove from heat and allow to sit for 5 to 10 minutes before serving.
