(And it's a pity you can't see it bubbling...)
That's the fat from merguezes! Better: those merguezes are home made by my Halal butcher just down the street! I love to buy my lamb at the Halal butcher because it has more taste that the lamb that is normally sell in Italy: too young for our fine palates... They have wonderful legs of lamb (which I normally roast), any piece from the lamb and merguezes, that sometime we buy even if we don't make couscous: they are just wonderful all by their own, grilled, served with some potatoes.
And this time I made them in a kind like pie.
I boiled some potatoes, then mash them, add some milk (goat milk in this case), some grated emmental, some butter, salt and pepper and cook it for a few minutes. Then I placed some cut merguezes in the bottom of a oven dish, covered everything with the mash, sprinkled with some grated emmental and cooked in the oven for about 20-25 minutes.