A 5 ingredient creamy pasta sauce that doesn't lack flavor. You can pair it with pasta or serve as a warming soup.
In a heavy-bottomed pot, heat oil over medium-high. Add sage and cook for 1 minute until fragrant, stirring occasionally, making sure it doesn't burn. Add onion, garlic, squash, red pepper flakes, salt, and pepper. Stir to combine mixture. Cook for 8 minutes until squash has developed some color and onions are soft and translucent.
Pour in vegetable broth and bring the mixture to a simmer. Cook for 4-5 minutes until squash is completely soft when a fork is inserted. Carefully transfer the mixture to a high-powered blender. Blend until smooth and creamy. Adjust seasoning with salt and pepper as needed.
Cook pasta according to package directions. Drain and add back to its cooking pot. Pour in desired amount of sauce and stir to combine. If you have any leftover sauce, save for pasta or soup at a later time.
(Optional): Toast walnuts over medium-high in a small skillet. Add to a small bowl and toss with lemon zest and a pinch of flaky sea salt. Top pasta with walnut mixture.