01 - Preheat oven to 425°F. Line a large baking sheet with parchment paper.
02 - Toss delicata squash and red onion slices with olive oil, salt, and pepper. Spread evenly on the prepared baking sheet. Roast for 25–30 minutes, flipping halfway through, until golden and tender.
03 - While vegetables roast, combine quinoa and vegetable broth in a medium saucepan. Bring to a boil, then reduce heat to low, cover, and simmer for 15 minutes. Remove from heat and let stand, covered, for 5 minutes. Fluff with a fork.
04 - Melt butter in a small skillet over medium heat. Add sage leaves and cook, swirling occasionally, until butter turns golden brown and sage becomes crisp, about 3–4 minutes. Remove from heat immediately to prevent burning.
05 - Divide quinoa among 4 bowls. Top with roasted delicata squash, red onion, and baby spinach. Drizzle with sage brown butter.
06 - Finish with crumbled feta cheese, toasted pumpkin seeds, and additional salt and pepper to taste. Serve warm.