Clean the mushrooms and cut them in half or quarters depending on their size.
Finely dice one onion, mince garlic, and thinly slice sun-dried tomatoes.
Melt butter in a pot and sauté onions for 5 minutes over low to medium heat, then add mushrooms and tomatoes. Sauté for another 3-5 minutes until soft, add garlic and leave it for one more minute. Then add the flour, and keep stirring for another 2 minutes.
Add milk and water, white beans, vinegar, and thyme, and bring to a boil. Simmer for 10 minutes, then add spinach and cream, and season to taste with salt and black pepper. If needed, add more water to make the sauce thinner.
Serve with some ice bread for dunkings, drizzle with some olive oil and enjoy!