Here's a fantastic recipe from Cook's Illustrated magazine. It somehow manages to be both creamy and cheesy AND light and fresh tasting. Amazing. The recipe calls for fusilli pasta, but I used rotini. Perfection! It's like unstuffed shells.
11 oz whole-milk ricotta cheese (I used a whole 16oz container)
3 tbsp extra-virgin olive oil
Salt and pepper
1 pound pasta
1 pound baby spinach, chopped coarse
4 garlic cloves, minced
1/4 tsp ground nutmeg
1/8 tsp cayenne pepper
1/4 c heavy cream
1 tsp grated lemon zest plus 2 tsp juice (I used more)
1 oz Parmesan cheese, grated, plus extra for serving (I used more)
Whisk 1 cup ricotta, 1 tablespoon oil, 1/4 teaspoon pepper, and 1/8 teaspoon salt in a medium bowl until smooth; set aside.
Bring 4 quarts water to boil in a large pot. Add pasta and 1 tablespoon salt and cook, stirring often, until al dente. Reserve 1 cup cooking water. Stir spinach into pot with pasta and cook until wilted, about 30 seconds. Drain pasta and spinach and return them to the pot.
While pasta cooks, heat remaining 2 tablespoons oil, garlic, nutmeg, and cayenne in a saucepan over medium heat until fragrant, about 1 minute. Remove pan from heat and whisk in remaining ricotta, cream, lemon zest and juice, and 3/4 teaspoon of salt until smooth.
Add ricotta-cream mixture and Parmesan to pasta and toss to combine. Let pasta rest, tossing frequently, until sauce has thickened slightly and coats pasta, 2-4 minutes, adjusting consistency with reserved cooking water as needed. Transfer pasta to serving platter, dot evenly with reserved ricotta mixture, and serve with extra Parmesan.