Incorporate the cold butter using your fingertips or a pastry cutter; alternatively, use a stand mixer with the dough hook attachment. Mix until the flour resembles coarse crumbs. Add the grated cheese and mix until it is distributed evenly. Drizzle in the cold water, one tablespoon at a time, stirring just until the dough begins to form. It should hold together without being sticky. 

If mixing manually, turn the dough out onto a lightly floured surface and knead gently to form a smooth ball. Alternatively, mix in the mixer until it becomes dough. 

Roll the dough into a thin rectangle, about 2 mm thick. Lift and place onto a floured baking tray, and then cover with cling wrap and chill in the fridge for at least 30 minutes to firm up and make cutting easier. Note that the crackers will rise slightly when baking, so the dough needs to be thinly rolled out, or the crackers will be too thick. 

Preheat the oven to 190 °C. 

Unwrap and place the chilled dough onto a floured surface. Trim into a neat rectangle, and then use a sharp knife to slice into small squares, triangles, or your desired shape. Re-roll the dough until it has all been used – you should have about 40 crackers. Arrange the pieces on a baking sheet/tray lined with baking paper, leaving some space between them