Peel off the loose papery skin on the outside of the garlic head. Slice the top off of the garlic head to reveal the tops of each clove. Drizzle with the olive oil and wrap the head of garlic in foil. Place in the oven on the center rack and roast until caramel colored and tender, about 40 minutes.
Peel the potatoes, rinse and cube them into 2-inch pieces. Fill a large pot with cold water and add potatoes along with the bay leaves. Bring the water to a boil over high heat, turn the heat to low and simmer until potatoes are just fork tender, but not falling apart.
Using a colander, drain the potatoes. Add the potatoes back to the pot and place it back on the heat. Keep the burner on the lowest heat setting until the potatoes have completely dried out. The dryer the potatoes get, the more liquid they will reabsorb. Remove the bay leaves at this time.
Using a ricer or potato masher, mash potatoes. Gently squeeze the cloves from the roasted garlic into the mashed potatoes and mix until smooth.
In a small sauce pan melt the butter and milk together until both are hot, but not boiling. Using cold dairy will compromise the texture of the potatoes.
Add the milk-butter mixture to the potatoes stirring quickly with a large spoon until fully absorbed. Generously season with salt and pepper to taste.