Bake the yams in a 400° F. oven for 45 minutes, or until tender.
Scoop out the flesh and mash it with the brown sugar, amaretto liqueur, 2 tablespoons of the butter, and the salt.
Spread the yam mixture in a 9-by-9-inch baking pan.
Pulverize the amaretti cookies between 2 pieces of wax paper; blend in the remaining 2 tablespoons of butter.
Sprinkle the cookie crumbs on the yams.
Preheat the oven to 350° F., and bake the yams for 30 minutes.