Combine flour, salt, yeast, and water in a large bowl. Mix until dry ingredients are incorporated. (The bowl should big enough that the dough can double in size when proofing.)
Cover the bowl with either plastic wrap or a towel and let sit for 6-8 hours at room temperature. (You may also refrigerate overnight or for up to 24 hours, in which case use plastic wrap and wrap tightly.) If the dough does not rise or get bubbly, throw away the dough and start from scratch.
Once the dough has rested, flour a work surface and your hands then lightly knead the dough. Fold and repeat the process till it is a tight ball and tuck the edges underneath so that the top is smooth.
Coat the bottom and sides of the baking vessel using half of the olive oil-- I recommend baking in either a rectangular sheet tray or a cake pan.
Place your dough in the middle of the vessel and press down with your palm to slightly flatten the dough. Cover with plastic (again) and let sit at room temperature for 1½ hours.
In the meantime, preheat your oven to 350F. De-pit the olives and cut them into slices or rough chop. Pick rosemary leaves off of the stems.
Once the dough has proofed, it should be light and fluffy and should fill most of the pan. Using your fingertips, press down all around to release the bubbles that have appeared on the dough. Try to eliminate as many as you can.
Drizzle the remaining olive oil on top, then evenly spread olives along with rosemary leaves, pressing them in. Sprinkle just a tiny bit of maldon salt then place in the oven and bake until golden brown, about 20-35 minutes.
Remove from the oven, then use an offset spatula to check that the bottom is golden brown. Place on a wire rack to cool.