01 -
Throw the quartered onion into a blender and pulse for 2 seconds on speed 5. Use a spatula to scrape down the edges.
02 -
Toss in the butter, flour, milk, salt, pepper, nutmeg, and egg yolk. Heat for 8 minutes at 90°C, mixing on speed 4.
03 -
Mix 100 grams of grated Emmental cheese into the sauce and cook 1 more minute at 90°C, speed 4.
04 -
Butter up your baking dish. Cover the bottom lightly with some Mornay sauce. Then lay a layer of lasagna sheets, trimming if needed.
05 -
Spread a fourth of the Mornay sauce. Lay down 2 slices of ham, then a third of the raclette cheese.
06 -
Layer more pasta on top. Spread a third of the sauce, 2 more slices of ham, and the next portion of raclette cheese.
07 -
Add pasta again, half of the remaining sauce, 2 slices of ham, and all the rest of the raclette cheese.
08 -
Top off with a final pasta layer and the last of the Mornay sauce. Sprinkle 40 grams of Emmental cheese on top. Preheat your oven to 200°C. Bake for 20 minutes until golden and bubbly.