Preheat oven to 425 degrees F.
Slice off the very top of the garlic head. Drizzle head with olive oil and wrap in foil. Place on a sheet tray and bake until tender and fragrant, roughly 35 minutes. Remove from the oven and let cool. Remove the cloves and mash with a wooden spoon.
Place potatoes in a large stockpot and cover with cold water. Add salt and bring to a boil. Cook until fork tender and drain. Mash the potatoes until smooth.
Meanwhile heat butter and cream until butter melts. Add the roasted garlic and potatoes and mash all together.
Taste and season with salt and pepper. Serve immediately.