First chop the onion and sweat it in olive oil until translucent. Chop a clove of garlic and fry briefly, then pepper. Then add the spinach. After about 15 minutes, it should be completely thawed. Press in the remaining cloves of garlic, add salt and pepper if necessary. Finally add the crème fraîche.
In the meantime, sear the salmon in the butter until it can be easily cut into pieces. Salt and pepper the salmon pieces. Add the salmon to the spinach and mix well. I put the whole thing out to cool down briefly so I don`t burn my fingers.
For the sauce, lightly fry the flour in the melted butter. Then slowly add the milk while stirring with the whisk. Finally, salt and pepper.
Now fill the cannelloni with the spinach mixture. I just do this with my fingers. Put the cannelloni in a greased baking dish. Unless you have a huge baking dish, it should be two layers.
Pour half of the bechamel sauce over the first layer. Then put the second layer on top and drizzle with the rest of the bechamel sauce. Cook at 210 ° C for 35 - 40 minutes.