Prepare the Ingredients

1. Preheat Oven: Preheat the oven to 400°F (200°C).
2. Roast Squash: Place the cubed squash on a baking sheet. Drizzle with 1 tablespoon olive oil, season with salt and pepper, and roast for 20 minutes until tender and golden. Set aside.

Cook the Pasta

3. Boil Pasta: Cook the pasta in salted boiling water until just al dente. Drain and set aside.

Make the Sauce

4. Sauté Aromatics: In a large skillet over medium heat, melt the butter. Add the diced onion and sauté for 3-4 minutes until translucent. Add the garlic, thyme, and sage, cooking for another minute.
5. Create Roux: Sprinkle the flour over the onions and stir for 1 minute.
6. Add Milk and Cream: Gradually whisk in the milk and heavy cream, stirring continuously until the mixture thickens. Season with salt and pepper.

Assemble the Bake

7. Combine Pasta and Spinach: In a large mixing bowl, combine the cooked pasta, roasted squash, and fresh spinach. Pour in the sauce and toss to coat evenly.
8. Transfer to Baking Dish: Spread the mixture into a greased 9×13-inch baking dish. Sprinkle the mozzarella and Parmesan cheeses on top.

Bake and Serve

9. Bake: Bake for 25-30 minutes or until the top is golden and bubbly.
10. Serve: Let cool for 5 minutes before serving. Garnish with extra Parmesan or fresh herbs if desired.