01 -
Place the peeled and quartered onion in a blender. Blend for 2 seconds at speed 5, then scrape down the sides with a spatula.
02 -
Add butter, flour, milk, egg yolk, salt, pepper, and nutmeg to the blender. Cook for 8 minutes at 90°C on speed 4.
03 -
Add 100 grams of grated Emmental cheese to the sauce and cook for another minute at 90°C on speed 4.
04 -
Butter a gratin dish and spread a little Mornay sauce on the bottom. Place a layer of lasagna sheets on top, adjusting as needed.
05 -
Spread 1/4 of the Mornay sauce, then place 2 slices of ham and 1/3 of the raclette cheese.
06 -
Add another layer of pasta, 1/3 of the remaining sauce, 2 slices of ham, and more raclette cheese.
07 -
Repeat with pasta, half of the remaining sauce, 2 slices of ham, and the remaining raclette cheese.
08 -
Finish with a final layer of pasta and remaining Mornay sauce. Sprinkle with 40 grams of Emmental cheese. Preheat oven to 200°C and bake for 20 minutes until golden brown and bubbly.