01 -
Preheat oven to 430°F. Toss cubed butternut squash with 1 tablespoon olive oil and salt. Spread on a baking sheet and roast for 25–30 minutes, stirring halfway through, until soft and caramelized.
02 -
Heat 2 tablespoons olive oil in a pan over medium-low heat. Add diced garlic and cook gently, stirring frequently to prevent burning. Add chili flakes and continue cooking for 1 to 2 minutes while stirring.
03 -
Cook gluten-free spaghetti according to package instructions, reducing cooking time by one minute to ensure firmness. Drain and set aside.
04 -
Mash half of the roasted butternut squash using a fork or potato masher. Add both mashed and whole squash pieces to the pan with garlic and chili mixture, stirring to combine.
05 -
Add drained spaghetti and fresh spinach to the pan. Toss thoroughly to coat pasta and wilt spinach evenly with the pumpkin sauce. Season with black pepper, lemon juice, additional salt, chili flakes, and extra olive oil if desired.
06 -
Transfer to serving plates and garnish with chopped walnuts and lemon zest. Serve immediately.