Preheat oven to 400 degrees F.
Remove the outer layer of skin from the garlic head, the skin that is flaky and papery. Don’t remove all of the garlic skin because you want the garlic head to keep its shape.
Slice off the very top of the garlic head. Drizzle garlic with olive oil and wrap in foil. Place on a baking sheet and bake until tender and fragrant, about 35 minutes.
Remove from the oven and let the garlic cool to room temperature.
While the garlic is roasting, peel the potatoes and cut into 1-inch pieces. Place potatoes in a large pot and cover with cold water. Add ½ teaspoon salt and bring to a boil. Continue to simmer until potatoes are fork tender, but not falling apart. Check at 15 minutes to be safe, it might take a little longer.
Drain the potatoes, shaking to make sure all of the water is removed. Place the drained potatoes back in the pot.
Remove the outer layer of each roasted garlic clove and add the roasted garlic cloves to the pot with the potatoes. Place the potatoes and roasted garlic through a ricer until potatoes are smooth. If you don’t have a ricer, you can mash the potatoes and garlic together with a potato masher.
In a small pan, warm the half and half and butter together. Stir the mixture into the potatoes until combined. Don’t over mix or your potatoes will get stiff and gummy. Season with salt and black pepper, to taste. Garnish with fresh chives and serve warm.