Heat the oven to 500 degrees Fahrenheit. Place a large baking sheet in the oven to warm.
Remove the dough from the refrigerator, punch it down and separate into four separate pieces.
If you are adding crackling: Cube in small squares the crackling (pig or duck's fat). In a skillet, cook as you would bacon - rendering the fat and cooking it until crisp. Drain the fat and keep the cooked crackling.
Add the olives or crackling, if you are using these ingredients, to the dough now before you roll it out.
Roll each ball into a rectangle of about 8 x 5 inches (approximate). Cut three slashes in each bread dough and gently open up the slashes, enlarging the slashed areas. Brush with each bread dough with olive oil
Reduce the heat of the oven to 450 degrees and place the bread (which should be put on parchment paper on a baking sheet) onto the hot pan in the oven. Bake for 25-30 minutes until golden brown.