1Bring 4 cups of salted water to a boil.
2Peel onions and cut into quarts. Place into boiling water (about 5 minutes before the fennel).
3Clean the fennel and cut it into eights. Add to onion in boiling water and cook for 15 minutes, remove from water and set aside to cool off.
4In a skillet, large enough to accommodate all ingredients, melt the butter then mix together fennel and onion, season to taste with salt and pepper. Cook for 2-3 minutes while jumping them around then remove from heat.
5Preheat oven to 350Fº.
6Prepare 1 cup of Besciamella (see recipe below).
7Butter a 8” by 10” ovenproof pan or a 14″ cast iron pan, sprinkle with bread crumbs and layer half of onion and fennel.
8Mix together Besciamella and Gruyere cheese, pour half of it on top of vegetables and season very lightly with some nutmeg.
9Cook in the oven uncovered for about 25 minutes then broil for 3-5 minutes, until breadcrumbs are golden and toasty.
11Remove from oven and let rest for a few minutes before portioning. Serve warm, garnished with a few fennel fronds and seasoned with freshly grated pepper.
1In a medium size pot melt the butter over a low flame, then sift the flour in and stir well.
2Cook for a couple of minutes until ingredients start to lightly darken, slowly pour in the milk and season with nutmeg, salt and pepper.
3On a very slow fire cook until the sauce starts thickening (about 10 min), taste to adjust seasoning then remove from fire and set aside.
Besciamella cannot cool off in the pan it was made in otherwise it will stick. If you do not intend to use it right away, cool it off in a ceramic bowl. It also requires to be warmed up at Baine Marie as microwave or stovetop will thicken it too much.
This recipe lands itself well to individual vessels for serving, like small cast iron pots.
You can assemble this recipe and freeze it for up to 3 months. Thaw overnight in the refrigerator and cook the day after as instructed.