Heat the butter and olive oil in a large saucepan over medium heat. Add the onion and sauté for 3 minutes or until soft and translucent. Add the minced garlic and cook for a further minute.
Sprinkle over the flour and beef stock powder. Cook, stirring, for 2 minutes. Pour in the liquid chicken stock, stir and bring to a low simmer for 15 minutes.
Spoon out and reserve 2 cups of the soup in a jug or bowl. Set aside (this step is for a chunky mushroom soup, however if you want a smooth soup - leave this step out).
Use a stick blender to puree the remaining soup. Add the reserved soup and the cream to the pureed soup. Season with salt and pepper and mix to combine.