MAKE THE DOUGH
In mixing bowl, whisk together 2 1/4 cups of the flour and 1 teaspoon of salt; set aside.
In separate small bowl, stir together water, sugar and yeast. Let sit for several minutes until foam forms on top.
Make a well in center of flour and add the yeast mixture; stir until combined. If using an electric mixer, add hook attachment and knead for several minutes until dough pulls away from the sides and has an elastic texture. If kneading by hand, roll out on to floured surface and knead by hand for 10 minutes.
Add 1 tablespoon of olive oil to large bowl. To that same bowl, add the dough and roll to coat dough in olive oil.
Cover top of dough with plastic wrap and then cover the top of the bowl with a clean towel.
Let rise for a least 90 minutes, until dough has doubled in size.
Punch dough down and break in half to form two dough balls.
If using right away, let rise another 30 minutes on counter. If using at a later date, place in greased plastic ziplock and refrigerate for up to 3 days.
Fill a large sauce pan with water and add a little salt. Bring to a boil. Add the cauliflower and cook for about 5 minutes. Drain the cauliflower and set aside.
ASSEMBLE THE SCIACCIATA
When ready to make the sciaciatta, heat oven to 425 degrees F.
Grease 9-inch spring form pan, or shallow pie or pizza pan with olive oil.
Roll out both pieces on a lightly floured surface – one should be larger than the pan, the other the size of the pan. Press the larger piece of dough into it, making sure it comes up the sides. Drizzle the dough with a little bit of olive oil and rub it in (or use a pastry brush to brush all over the surface of the dough).
Arrange the cauliflower florets (if after you boil the cauliflower you find the florets too big, when it cools a little, you could cut into even smaller pieces) evenly over the dough.
Next, add on the onion slices, olives and anchovy filet pieces. Sprinkle on salt and pepper.
Brush the edges with oil, then cover with the remaining dough.
If there are any large portions of dough cut with a pastry cutter. Pinch the two doughs together to seal in the filling. Go around the dough with a fork and press the perimeter of the dough closed.
Poke the surface of the top layer with a fork every few inches.
Brush the top of the dough with olive oil mixed with a little bit of water (you could also brush it with a beaten egg).
Bake for 30-40 minutes or until the top gets golden brown.
Let it rest for 20 minutes before carefully removing it from the pan and slicing.