Melt your butter in a large skillet over medium-high heat. Add in mushrooms, onion and garlic; Sauté for 4-5 minutes, stirring frequently.
Stir in all the herbs and seasonings, then add the wine. Allow it to simmer over medium heat for about 2-3 minutes.
Meanwhile, in a small bowl, whisk your coconut milk and arrowroot powder or gf flour together really well, until there are no lumps.
Transfer the mushrooms to the slow cooker, together with the broth and your coconut milk mixture. Season with sea salt and pepper and stir well to combine.
Cover and cook on HIGH for 2 to 2-1/2 hours or LOW for 3 to 4 hours.
Once your soup is ready, add half of it to a high speed blender and blend until smooth and creamy.
Return the creamy soup to the slow cooker and stir in with the other remaining half.
Garnish with freshly chopped parsley and serve while hot.