Directions

1. In a large skillet, melt butter and olive oil over medium heat. Add shallots and garlic; sauté for 1 minute until fragrant. Add spinach in batches, stirring until wilted and any liquid evaporates. Season with salt and pepper. Transfer to a fine-mesh strainer and press out excess moisture.
2. In a food processor, blend half of the ricotta with eggs, Parmesan, nutmeg, salt, and pepper until smooth. Transfer to a large bowl. Pulse the cooked spinach in the food processor until finely chopped, then fold it into the ricotta mixture with the remaining ricotta.
3. Melt butter in a saucepan over medium heat. Add flour and whisk for 1 minute until lightly golden. Gradually add milk, whisking constantly until smooth and thickened. Remove from heat and stir in ¾ of the mozzarella and Gruyère cheeses. Season with salt and pepper.
4. Bring a large pot of salted water to a boil. Par-cook pasta sheets for about 45 seconds, then transfer to cold water. Lay out on kitchen towels to dry.
5. Preheat oven to 400°F (200°C). Lightly grease a large baking dish.
6. Spread a thin layer of white sauce on the bottom.
7. Add a layer of noodles, then a layer of spinach-ricotta filling, followed by white sauce.
8. Repeat until all layers are used (about 12 total), finishing with sauce and a sprinkle of remaining cheeses on top.
9. Cover with foil and bake for 20 minutes. Remove foil and continue baking for 20–25 minutes, until golden and bubbling.
10. Let rest 10 minutes before slicing and serving for the perfect set layers.