Toss butternut squash with 2 tablespoons oil and 1/2 teaspoon salt, then arrange in 1 layer in a 17- by 12- by 1-inch baking pan and roast, turning occasionally, until golden brown on edges, 20 to 25 minutes.
Meanwhile, toast pumpkin seeds in 1 tablespoon oil in a large heavy skillet over medium-high heat, stirring frequently, until seeds are puffed and beginning to brown, 2 to 4 minutes. Transfer to a large plate and cool.
Pulse cooled seeds in a food processor with cilantro, lemon juice, 1/4 teaspoon each of salt and pepper, and remaining tablespoon oil to a coarse paste (not finely ground).
Toss squash with pesto and salt and pepper to taste. Serve immediately.
Per serving: 205 calories, 14 g fat, 2 g saturated fat, 0 mg cholesterol, 8 mg sodium, 19 g carbohydrates, 3 g fiber, 4 g proteinSee Nutrition Data's complete analysis of this recipe › Nutritional analysis provided by Nutrition Data