1. Cut the cauliflower into small florets and cook them in salted boiling water until very tender (a knife should easily penetrate them).
2. Drain them and set aside half of the cauliflower (save the rest for another use, such as a gratin).
3. Mash the cauliflower florets with a fork to obtain a coarse puree. Stir in the cream and two whole eggs, season with salt, pepper, and grated nutmeg.
4. Finally, add two tablespoons of grated Parmesan cheese and mix well.
5. Bring a large pot of water to a boil, add salt, and cook the lasagna sheets for 2 or 3 minutes (just enough to soften them).
6. Then remove them with a slotted spoon and let them drain flat on a towel, avoiding overlapping.
7. Preheat the oven to 180°C (350°F).
8. Cut the Gex blue cheese into cubes.
9. Arrange a first layer of lasagna sheets at the bottom of a gratin dish and cover it with one-third of the cauliflower puree.
10. Scatter half of the blue cheese cubes, then repeat: a layer of lasagna sheets, the second third of the puree, the remaining blue cheese cubes. Finish with lasagna sheets topped with the remaining cauliflower puree.
11. Generously sprinkle the lasagna with grated Parmesan cheese, sprinkle with walnut kernels, and bake. Cook for 25 to 30 minutes and serve hot. Enjoy!