Place the ground beef, rosemary, parsley and ½ teaspoon sea salt into a medium sized frypan. Over a low-medium heat, stir and break up the beef until it has crumbled and is browned. Add the mushrooms, gently mix through, and continue cooking for 10 minutes, stirring occasionally. Remove from the heat.
Place the pumpkin, celery, carrot, chives, bone broth, water and 1 1/2 teaspoons sea salt into the Instant Pot or into a large pot.
If using the Instant Pot, secure the lid, turn the valve to 'Sealing', and set the Manual function to 5 minutes. When the timer sounds, allow to the pressure to release naturally. If using a saucepan on the stovetop, bring to a boil, reduce the heat and maintain a simmer for 15 minutes.
Using an immersion blender, whiz the soup to a velvety consistency.
When ready to serve, heat both the soup and the crumble, adding a little extra virgin olive oil to the crumble if desired. Ladel the hot pumpkin soup into pre-warmed bowls, and top with the crumble.