Peel the potato and dice coarsely. Cut the cored cauliflower into small pieces. Place both in a pot and barely cover with water.
Bring to a boil. Cover and reduce heat. Simmer 20 to 25 minutes until very tender. Drain and save 1/3 cup of the liquid.
Smash the garlic clove with the flat side of a knife and mince. Add to the pot along with the reserved liquid and cook on medium heat until soft.
Return potato and cauliflower to the pot and mash roughly with a potato masher. Season with salt and pepper and stir until heated through. Sprinkle with grated parmesan cheese and chives before serving.
HINT: To freeze chives when you have more than you can use, make sure they are completely dry, chop them up to whatever size you want, spread them out on a flat pan or cookie sheet and put them in the freezer. When frozen, scoop them up and store them in a tightly sealed jar or a freezer bag. They will be nice and loose in the container and you can easily take out the amount you need for cooking.