Place butter and coconut oil in a deep soup pot and melt over medium heat.

Peel each onion and cut in half lengthwise. Lay face down and halve lengthwise again, then slice thinly crosswise. Add the onions to the pot, stirring to coat in the melted fats.

Gently cook the onions over low to medium heat for about 20 minutes, stirring often. They should all turn a light brown color and become very aromatic. If you wish to continue until they caramelize, cook for another 20 minutes or so until very soft and browned, stirring as needed to prevent burning.

Turn heat up to medium-high. Add grated potato to the onions and cook for 2 minutes, stirring well. Stir in salt and pepper.

Stir in broth, bring to a simmer and cook on medium for 5 minutes. Turn off the heat.

Cut the round of Camembert cheese in half. Holding one of the halves over the pot, use a teaspoon to scoop out the creamy inner cheese and drop into the hot soup. Repeat with other half round of cheese.

Using an immersion blender or a standing blender, carefully blend the soup to a creamy consistency. Taste and adjust seasonings. Serve hot.

If desired, add the cream just before serving and stir well; or place the cream on the table and let each eater add it as they wish. It really increases the richness of the soup.

Yields 2 quarts