Cook pasta according to package directions, omitting salt and fat. Drain in a colander over a bowl, reserving 1/2 cup cooking liquid.
Heat a large skillet over medium-high heat. Add oil; swirl to coat. Add shrimp, fennel, and shallots; sauté 3 minutes. Add garlic; sauté 30 seconds. Add spinach; cook 2 minutes or until spinach wilts.
Stir in rind and next 3 ingredients (through salt). Stir in reserved cooking liquid; cook 1 minute or until slightly thickened. Add pasta and Parmesan cheese; toss to coat. Top each serving with 1 tablespoon ricotta.