First you need to wash your squash really well. Be sure to remove all traces of soil from the skin. Next slice your squash into medium sized slices, and set aside. I chose to slice mine in the round but I suppose anyway you like is fine. Next fill a large pot about half full with water and, set it on the stove to bring to a boil. Meanwhile while your water is heating up, prepare a large bowl full of ice water. This needs to be really cold. Place this bowl within reaching distance of your pot of boiling water.
After your water comes to a boil, toss in the squash in a blanch them, which is just a fancy way of saying boil for 3-4 minutes. Be sure to time this, you do not want to cook your squash to a mush. Using a slotted spoon scoop out the squash and immediately place it in the ice bath. This process stops the cooking. Add ice as needed to keep the water cold. Once your squash is completely cold, pour through a strainer, to remove the water. Shake off as much excess water as possible. I allowed mine to sit for just a moment in a bowl, allowing any extra water to drip off. If too much water is left on it will freeze into a solid block, and be just about impossible to take just what you want or need.