The Scacciata that I know is two layered, with the crust both on the bottom and top. I haven't made it myself, but this recipe comes very close to what I know. If you can get a ready made bread dough, should be quite easy to make.
Hope this one helps...
About 800 g (2lb) fresh bread dough (either make your own or buy it from your baker)
250 g (1/2lb) mild Caciocavallo or Provolone (mild), shredded
100 g (3,5oz) fresh lard or good quality evoo
75 g (2,5oz) salted anchovy filets, rinsed, pat dried
3 ripe plum tomatoes, peeled, seeded, sliced
An onion, thinly sliced
10 black olives, pitted and chopped
Salt and pepper to taste
Preheat your oven to 190C°/375°F.
Briefly knead the dough and divide it into two pieces, one somewhat larger than the other.
Roll the larger one out and use it to line a pie pan/flat round form of about 25cm/10in. diameter. Arrange the cheese over the dough, followed by the tomatoes, anchovies, and olives.
Lay the sliced onion to cover the surface, sprinkle with half the lard/oil, and season lightly with salt and pepper.
Roll out the second piece of dough and use it to cover the pie,sealing the edges with a fork so they stick.
Lightly coat top of the pie with the remaining lard/oil, make a few holes in the crust with a fork to let the steam escape, and bake the scacciata for about 40 minutes. Serve it hot.