Begin by peeling and chopping the 4 large russet potatoes into even chunks. Place them in a large pot filled with salted water, then bring it to a rolling boil over medium-high heat. Cook the potatoes until they are fork-tender, which should take about 15 to 20 minutes.

Once the potatoes are tender, drain them well and return them to the pot. Add ½ cup of heavy cream and ¼ cup of melted butter to the potatoes, then season with salt and pepper to taste. Use a potato masher or hand mixer to mash everything together until the mixture is smooth and creamy.

Now comes the fun part—shaping the mashed potatoes into skulls! If you have a skull mold, spoon the mashed potatoes into it, packing them tightly. If you’re shaping by hand, take a portion of the mix and mold it into a skull shape, ensuring it's well-defined.

Slice black olives into small circles to create the eyes for your spooky skulls. Carefully press two olive slices into the appropriate spots on each skull. Use additional olive pieces to form a mouth or other facial features.

If desired, chop up fresh chives or green onions for a vibrant garnish. Sprinkle them over the tops of your spooky skull potatoes for an extra splash of color. Serve them warm.