Blanching and shocking the collards preserves their vibrant color in the pesto and removes the greens’ slight bitter edge. Use best-quality peanuts; their toasty, nutty flavor is the foundation of the creamy pesto.
Preheat oven to 450°F with oven rack in lowest position. Toss together squash, 2 tablespoons oil, 1/2 teaspoon kosher salt, and 1/4 teaspoon pepper on a rimmed baking sheet. Spread in a single layer. Roast in preheated oven on lowest rack until squash is tender and browned, 26 to 30 minutes, flipping squash after 18 minutes.
Meanwhile, bring 8 cups water to a boil in a medium saucepan over high, and fill a bowl with ice water. Stir in 1 tablespoon kosher salt to the boiling water. Add collard greens; cook until tender and bright green, about 2 minutes. Transfer collard greens to ice water; let cool 2 minutes. Drain and pat greens completely dry; set aside.
Cook peanuts in a small skillet over medium, stirring often, until fragrant, 4 to 5 minutes. Set aside; let cool 5 minutes.
Place greens, peanuts, miso, lemon juice, and garlic in a food processor; pulse until a chunky paste forms, about 10 times. With food processor running, gradually stream in remaining 1/2 cup oil until well combined, about 20 seconds. Add remaining 1/2 teaspoon kosher salt and remaining 1/4 teaspoon pepper; pulse to incorporate, about 3 times. Spoon into a small serving bowl.
Arrange roasted squash on a serving platter; sprinkle with lemon zest, and garnish with flaky sea salt. Serve with pesto.
Pour a thin layer of olive oil over the pesto, cover, and refrigerate up to 1 week.
Substitute any hard winter squash, such as butternut or delicata, here.
Made this exactly as the recipe reads - really easy and so good! I made the pesto a couple of days in advance and put a little olive oil on top as suggested, worked perfectly!