How should I go about finding the Albanian national dish, tavë kosi?

I'm currently travelling in the Balkans and have previously had surprising difficulty finding the national dish in some countries.

Here in Albania the national dish is tavë kosi, baked lamb and rice with yoghurt sauce, which to me sounds divine.

But so far in Shkodër, Tiranë, Durrës, and Berat it never seems to be on the menu in typical little street restaurants or even in the two slightly more expensive traditional restaurants aimed at tourists that I've visited.

What does a gastronomic tourist need to know to find tavë kosi in Albania? Is it perhaps seasonal, only made in the home, only available on certain days of the week, only common in certain areas, more likely to be found in fancy expensive restaurants, or in small street ones that a tourist might not spot easily?

If it is more common in some regions, I'm currently in Berat and will visit Sarandë and possibly Gjirokastër.

(I have tried tavë dheu which seems to often be suggested as an alternative but it contains offal, which I'm not a great fan of)