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1
In large saucepan, heat oil over medium heat.
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2
Add leeks and cook, stirring often, until softened, 3 to 5 minutes.
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3
Add squash and cook, stirring, 1 minute.
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4
Add broth and bring to a simmer.
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5
Reduce heat to medium-low, cover and cook until squash is just tender, 8 to 10 minutes.
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6
Stir in vinegar and pepper.
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7
Set aside.
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8
In food processor, combine walnuts and bread crumbs; process until walnuts are ground.
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9
Add parsley and salt to taste; pulse until blended.
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10
Transfer to medium bowl and set aside.
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11
Wipe out food processor.
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12
Bring large pot of lightly salted water to a boil.
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13
Preheat oven to 425F.
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14
Coat 13 x 9-inch or other 3-quart baking dish with cooking spray.
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15
Make cream: In medium saucepan, bring broth to a simmer over medium-low heat.
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16
Add garlic, cover and simmer until tender, 15 to 20 minutes.
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17
Transfer to food processor.
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18
Add tofu, oil, mustard, cayenne and salt and pepper to taste; process until smooth.
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19
Set aside.
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20
Add pasta to boiling water; stir to prevent sticking.
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21
Cook, stirring often, until barely tender, about 4 minutes.
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22
(Pasta will be quite firm.)
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23
Drain, rinse under cold running water, then drain again.
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24
In large bowl, combine pasta and reserved cream; mix with rubber spatula.
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25
(Mixture will be soupy.)
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26
Spread half the pasta mixture in prepared baking dish.
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27
Spread with reserved squash mixture, then sprinkle with half the walnut topping.
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28
Top with remaining pasta mixture and remaining walnut topping.
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29
(Gratin can be prepared ahead to this point.
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30
Cover and refrigerate up to 2 days.
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31
Bring to room temperature before baking.)
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32
Bake gratin, uncovered, until golden and bubbly, 20 to 30 minutes.
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33
Serve hot.
