Slice the mushrooms and finely chop the onion and garlic so they are ready to go into the pot.

Melt the butter in a saucepan and sauté the chopped onion and garlic over medium heat until the onion turns soft and translucent.

Add the sliced mushrooms and sauté over medium-high heat, stirring occasionally, until they release their moisture and turn deeply golden brown.

Sprinkle the flour over the mushroom mixture and stir continuously, cooking for a couple of minutes until the raw flour smell disappears.

Gradually whisk in the vegetable stock and milk to avoid lumps, then bring the mixture to a gentle boil, stirring frequently.

Reduce the heat and simmer the soup, stirring occasionally, until it visibly thickens enough to coat the back of a spoon.

Let the soup cool slightly, then blend it to a smooth, velvety consistency using an immersion blender or a countertop blender.

Return the soup to low heat, stir in the fresh cream, black pepper, and salt, and turn off the heat as soon as it is warmed through.

Let the soup sit off the heat for a couple of minutes so the flavors settle, then ladle into bowls and garnish with chopped parsley.