- Place peeled and cut potatoes in a large bowl and cover with cold water. Let them sit for a few minutes, then drain and rinse 2–3 times with fresh cold water, or until the water runs mostly clear.
- Transfer the potatoes to a large pot and cover with fresh cold water by 1–2 inches. Bring to a boil over high heat, then reduce the heat to maintain a gentle simmer. Cook until the potatoes are completely tender and offer no resistance when pierced with a knife.
- Drain the potatoes in a colander and let them sit for 1–2 minutes to release excess steam.
- Meanwhile, combine the milk and 6 tablespoons butter in a small saucepan over low heat. Warm until the butter is melted and the milk is warm. Do not boil.
- Pass the potatoes through a potato ricer or food mill, or mash thoroughly with a potato masher. Gradually fold the warm milk and butter mixture into the potatoes with a rubber spatula.
- Note: reserve 2–3 tablespoons of the milk and butter if using the spinach puree.
- Gently fold in the pesto. For a brighter green color, add a few drops of green food coloring or fold in the spinach puree (see Tips & Tricks). Add any remaining milk and butter mixture as needed until the potatoes are light and creamy but firm enough to hold their shape. Season with salt and black pepper to taste.
Preparing the Toast Points
- Preheat the oven to 400°F (204°C).
- In a small bowl, combine the softened butter, garlic, and chopped parsley. Spread the garlic butter evenly over one side of each slice of Italian bread.
- Arrange the bread on a baking sheet and bake for 6–8 minutes, or until lightly golden and crisp around the edges. Cut each slice diagonally into 4 small triangles to create toast points.
Serving Tips
- Transfer the warm mashed potatoes to a serving bowl and arrange the decorating ingredients nearby so everyone can create their own monster.
- To build a monster, use an ice cream scoop to portion the mashed potatoes onto a plate, creating a round monster head. Add black olive pieces for eyes, a cherry tomato half for a nose, parsley sprigs for hair, and garlic toast points for ears, or use the toppings however you like to create your own monster.
- Add warm marinara for a spooky “blood” effect, if desired, and enjoy your monster while the mashed potatoes are warm.

Tips & Tricks
Naturally green spinach puree: Place the baby spinach in a microwave-safe bowl. Cover and microwave for 1–2 minutes, or until completely wilted. Once cool enough to handle, squeeze out as much excess liquid as possible. Blend the spinach with 2–3 tablespoons (30–45 mL) of the reserved warm milk and butter mixture until smooth. Fold the puree into the mashed potatoes until evenly green.
Make it a party: For even more decorating options, add bowls of grated Parmesan cheese and mini pepperoni to your Monster Mash station.
Watch the consistency: Pesto and spinach puree add moisture, so add the milk and butter mixture gradually. The finished potatoes should be light and creamy but sturdy enough to hold their shape.
Storage: Store leftover mashed potatoes in an airtight container in the refrigerator for up to 3–4 days. Store decorating ingredients separately. Reheat the potatoes gently on the stovetop or in the microwave, adding a splash of milk as needed to loosen the consistency.