Cut the chicory root in small pieces and roast in an air fryer (200℃), oven or pan until dark brown.
Add the roasted chicory root, ground elder and mushroom liquid to a sauce pan and boil for 10 minutes. Strain and set aside and let it cool down to room temperature.
Make a brown roux by combining the oil and all purpose flour in a sauce pan and cook until brown.
Whisk in the cooled down liquid to the roux. Bring it back to a boil. Lower the heat and let it simmer for 15 minutes.
The sauce has the right consistency when it sticks to the back of spoon.
Add the salt, yarrow powder, wild garlic powder and pavement mushroom powder. Finish by adding the heavy cream.