Begin by peeling and chopping the large russet potatoes into 2-inch chunks. Place the cubed potatoes into a large pot, covering them with cold salted water. Bring the water to a boil over high heat, then reduce to a simmer. Cook the potatoes for 15-20 minutes until fork-tender.

Once cooked, drain the potatoes and return them to the pot. Add the heavy cream, melted unsalted butter, salt, and pepper. Mash until creamy and smooth.

Pack the potato mixture tightly into skull molds or shape by hand, ensuring they hold together. Place on a baking sheet lined with parchment paper.

Slice black olives in half for eyes and place onto the shaped skulls. Get creative with additional olive pieces for mouths and features.

Preheat oven to 375°F (190°C). Bake the decorated skull potatoes for 15-20 minutes until golden and crispy.

Remove from oven, allow to cool slightly, and garnish with fresh chives or green onions. Serve warm.