Coffee and Walnut Splodge Biscuits

These are American-style cookies; in other words, just dropped onto the baking sheet free-form. Try to use the instant espresso powder if you can: real coffee or instant coffee granules made up with water change the texture of the dough, and you end up with a slightly too cakey texture (or else a too-weak taste). There is an element of cakiness here, but an entirely desirable one.