During the height of sugar production in Brazil in the 16th and 17th Centuries, huge amounts of sugar were exported to Europe. The extraction process consisted of squeezing the cane to release the juice, which was then boiled. This was then poured into clay cone-shaped moulds called pão de açúcar (sugar loaf in Portuguese), where it then crystallized. Due to the similarity to those moulds to the hill, the Portuguese named it Pão de Açúcar.
Others gave Sugar Loaf different names. For example, Tupi Indians who lived in Rio de Janeiro called it pau-nh-açuquã, which meant “isolated, steep hill.” Frenchmen who invaded Rio de Janeiro called it pot de beurre (butter bowl).
See here to see photos of Sugar Loaf