Heat the oven: Preheat to 425°F (220°C). Line a large sheet pan with parchment for easy cleanup.
Prep the squash: Toss cubed squash with 2 tablespoons olive oil, salt, and pepper.
Spread on the sheet pan, leaving a space in the center.
Add the feta: Place the feta block in the center. Drizzle with 1 tablespoon olive oil. Scatter garlic slices, onion (if using), and sage leaves over everything.
Roast: Bake for 25–30 minutes, until the squash is tender and caramelized on the edges, and the feta is soft and lightly golden.
Cook the pasta: While it roasts, boil pasta in salted water until just al dente.
Reserve at least 1 cup pasta water, then drain.
Mash the pan sauce: Remove the sheet pan from the oven. Use a spoon to gently mash the feta with some of the roasted squash and garlic to create a creamy base.
Toss it all together: Add the hot pasta directly to the sheet pan. Sprinkle in lemon zest, a squeeze of lemon juice, and red pepper flakes if using.
Add 1/3–1/2 cup reserved pasta water and toss until glossy and saucy. Add more water as needed.
Finish with hot honey: Drizzle hot honey over the pasta and toss again. Taste and adjust salt, pepper, and lemon.
Serve: Top with extra sage, Parmesan, and nuts or seeds for crunch.
Serve warm.