Find a small sharp paring knife. (It might seem odd that a small knife could cut this large squash. But this is the safest method because it helps to prevent slippage that happens with a large knife.)
Cut around the middle width-wise (not lengthwise!). To cut it, pierce the knife into the squash and swing down, making small slices around the squash. Cutting it this way makes the longest strands or “noodles”.