Preheat oven to 375°F. Combine oil and garlic in ovenproof cup. Bake until garlic is soft, about 20 minutes. Set aside.
Meanwhile, place malanga and chicken stock in large saucepan and boil until tender, about 35 minutes. Add mixture to food processor in batches and puree with roasted garlic and oil until smooth. Add half and half to desired consistency.
Season to taste with salt and pepper. Place in serving bowls and swirl drops of olive oil on top to garnish.