Brown the meat in the hot frying butter, add the onion and garlic. Add tomato puree, steam.
Deglaze with red wine and add the pelati, bring to a boil, reduce heat.
Add sugar, oregano and thyme, cover and simmer for about 30 minutes, stirring occasionally. Season to taste with salt and pepper.
For the bechamel sauce:
Melt the butter. Add flour, cook on low heat, stirring constantly with a whisk, deglaze with milk. Bring to the boil while stirring constantly, add the Glarner Grüessli and season with plenty of Weiss Stöckli with truffle. Simmer for 5-10 minutes, season.
The layers of lasagna
Layer bolognese, lasagna sheets and bechamel sauce in buttered gratin dish. In between, spread half of the Sbrinz over the lasagna. Finish with bechamel sauce, spread remaining Sbrinz on top. Bake in the middle of the oven preheated to 200 °C for 30-40 minutes.
The lasagna can be prepared a day in advance. Cover and store in the refrigerator. Spread the last layer of Sbrinz on the lasagna just before baking to form a crispy crust.