- In a saucepan, melt the butter. Add the flour and cook for 1 minute over medium heat, stirring constantly. Add the milk and nutmeg and bring to a boil, stirring with a whisk. Season with salt and pepper. Cover and set aside.
- Meanwhile, in a large pot of salted boiling water, cook the pasta until al dente. Rinse under cold water and oil lightly. Set aside.
- In a large skillet, wilt the spinach with the garlic in 30 ml (2 tablespoons) of oil. Season with salt and pepper. Drain in a sieve and set in a bowl.
- In the same skillet, cook the shrimp for about 1 minute in the remaining oil. Season with salt and pepper. Set aside in a large bowl.
- With the rack in the middle position, preheat the oven to 180 °C (350 °F).
- In a 33 x 23-cm (13 X 9-inch) baking dish, spoon half the bechamel sauce and cover with a layer of noodles. Cover with the spinach and shrimp. Add a layer of noodles and the remaining bechamel sauce. Sprinkle with the cheese.
- Bake for about 20 minutes. Finish browning under the broiler for approximately 5 minutes.
Once the lasagna is assembled, you can keep it refrigerated until ready to bake.