Melt the oil in a saucepan. Add onions and herbs until fragrant and onions are translucent. Add the garlic, and sauté for another minute.
Remove from heat, and add to a food processor along with the pumpkin, arrowroot starch, vegetable broth, almond milk, salt, nutritional yeast, cashews, and red pepper flakes. Pulse until completely combined. Taste for seasoning, and adjust as needed.
Return to pan and bring to a simmer on low heat.
Make the pasta according to package instructions, and drain.
Toss drained pasta with sauce and serve immediately. Garnish with pumpkin seeds and fresh, chopped sage.