Creamy White Bean Mushroom Soup

0 Heat the butter and oil in a large soup pot or Dutch oven over medium heat. When the butter melts, add the leek and onion. Cook about 5 minutes, until softened.
1 Stir in the mushrooms and 1 ½ teaspoons salt. Cook, stirring, until the mushrooms soften and release their water. This should take 5-8 minutes. Stir in the garlic and thyme and cook a few seconds until fragrant. Add the cannellini beans, dried mushroom powder and Parmesan rind, if using, and pour in the stock.
2 Bring to a simmer, then adjust the heat so it doesn't boil. Simmer 15 minutes. Remove from the heat.
3 If you used a Parmesan rind, fish it out of the pot and discard. Scoop out about ½ of the soup and puree in a blender until very smooth. You can use an immersion blender if you have one and puree right in the pot, leaving some chunky pieces of mushroom.
4 Stir in the cream and parsley. Serve warm in bowls.