Put the porcini mushrooms in a small bowl and cover with boiling water. Let them sit for 15 minutes while you move on to the chopping.
Slice the white mushrooms, dice the shallots, and mince the garlic.
Add 2 tablespoons of butter to a soup pot and bring the heat to medium-high. Reserve ¾ cup of the mushrooms and put the rest in the pot with the shallot, garlic, and dried thyme. Cook for 8 minutes, then stir in the flour. Then add the porcini mushrooms along with the liquid they were soaking in, the wine, broth, soy sauce, miso paste, salt, and pepper. Bring to a boil then cover, lower heat to a simmer, and cook for 15 minutes.
Remove half of the soup and add it to a blender. Blend until smooth and return it to the pot. Add the cream and simmer for 10 minutes.
As the soup simmers, add the remaining butter and reserved mushrooms to a small frying pan and sauté on medium heat for 10 minutes.
When serving the soup, top each bowl with the extra mushrooms, fresh thyme, and lots of black pepper.