Stuffed Shells With Spinach — How To Make Spinach-Stuffed Shells

Ingredients

• 1 (12-oz.) package jumbo shells
• 1 large egg
• 1 (16-oz.) container ricotta
• 2 c. shredded mozzarella, divided
• 3/4 c. freshly grated Parmesan or pecorino, divided
• 1 (16-oz.) package frozen spinach, thawed and squeezed dry
• 1 tsp. fresh thyme leaves (optional)
• 1/4 tsp. freshly grated nutmeg, plus more for serving
• 1/4 tsp. freshly ground black pepper
• 1/4 tsp. crushed red pepper flakes
• 1/2 tsp. lemon zest (optional), plus more for serving
• 3/4 tsp. kosher salt
• 1 clove garlic, grated
• 2 tbsp. extra-virgin olive oil
• 6 cloves garlic, smashed
• 1/4 tsp. freshly grated nutmeg
• 3 c. marinara
• 1 tsp. granulated sugar
• Fresh herbs (such as parsley, basil, or thyme), for serving (optional)