Preheat the oven to 425 degrees F. Line a sheet pan with parchment paper for easy cleanup.
Spread the butternut squash out on the baking sheet. Drizzle with 1 tablespoon olive oil, ½ teaspoon salt, and ¼ teaspoon black pepper. Toss to coat. Arrange the butternut squash so that the pieces aren't overlapping each other.
Bake at 425F for 30-35 minutes, tossing halfway through. The squash will be golden and very tender when done.
Meanwhile, bring a pot of water to boil. Boil the tortellini according to package instructions. Drain and set aside.
In the same pot used to cook the tortellini, heat 1 tablespoon of olive oil over medium heat. Add the minced garlic and cook until golden and aromatic, about 1-2 minutes.
Return the tortellini to the pot. Stir in the ricotta cheese, the juice from the lemon (about 3 tablespoons), and the spinach. Cover with a lid and return heat to low, warming until the ricotta is hot and spinach is wilted.
Stir in the roasted butternut squash, parmesan, the zest from the lemon, and the fresh basil. Taste for salt and pepper and garnish with optional red peper flakes. a
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Notes
Tortellini: Package sizes for tortellini vary, so aim for 12-16 ounces. I have made this recipe using dry (shelf-stable) tortellini and fresh tortellini from the deli.
Butternut squash: Frozen butternut squash works but should be thawed first. Because frozen squash is par-cooked, it only takes 20-25 minutes to roast.
Storage: Refrigerate in a closed container for 4-5 days. The ricotta will dry up in the fridge, so add a splash of water before reheating in the microwave.
For a thinner sauce, add 3 tablespoons of water along with the ricotta and lemon juice.