In a large pot, heat a splash of oil over medium heat. Add the chopped onion and garlic, sautéing until translucent.

Add the sliced mushrooms and cook until they are soft and browned.

Stir in the asparagus pieces and cook for an additional 5 minutes.

Pour in the vegetable broth and bring to a boil. Reduce heat and let simmer for 20 minutes, or until the asparagus is tender.

Using a blender, carefully puree the soup until smooth. Return to the pot and stir in the heavy cream.

Season with salt, pepper, and thyme. Heat through and serve warm.