Preheat oven to 475. Place the sweet potatoes, chorizo, and garlic on a baking sheet. Top with the reserved oil and salt and pepper. Roast for 15 minutes or until sweet potatoes are tender.
Meanwhile, cook the pasta according to directions. Reserve ½ cup of the pasta water. Drain and place in a large bowl. Add the spinach, dried tomatoes, and sweet potato mixture and toss to combine.