My buddy Mark had a similar mess with his first cheese sauce. He used those little bullet blender cups and thought a quick rinse counted as soaking. The result was this weird, gritty sludge that just coated the spoon in a gross film. Reading @the_ray's description of gritty paste with oil slicks is dead on, that's exactly what it looked like. He spent more time scrubbing his blender than he did cooking. It was a solid lesson in not taking shortcuts with nuts.