Preheat the oven to 350°F (180°C).
If you are blending your own oatmeal from rolled oats, simply place the rolled oat in a blender or food processor and blend until you get a coarse flour.
Mix the oatmeal, finely chopped fresh rosemary, and salt in a bowl, and add the extra virgin olive oil.
Bring the water to the boil and add it to the bowl. Mix with a spoon and let it cool slightly. Then use your hands to form a dough. Feel free to add a bit more water if the dough feels too crumbly. Just add it a tablespoon at the time.
Roll out the dough until very thin (3mm) and cut in circles with a round cookie cutter ( I used a 3 1/16 in - 78mm cookie cutter). If the dough is a bit sticky, I normally roll it out on a baking sheet, to avoid using additional flour.If the dough is too crumbly, don't add too much water. Simply roll out a quarter of the dough at a time. Place the circles on a flat tray covered with a baking sheet, no extra grease required.
Bake until golden brown, for 15-20 minutes. If your oven doesn't cook evenly, make sure to turn the trays half-way through baking. Keep a close eye on the oatcakes in the last 5-8 minutes, to avoid overcooking them.
When the oatcakes are ready, remove from the oven and allow to cool on a wire rack.