In a large pan over medium heat, place the oil and heat it until it shimmers.
Add the onions to the pan and stir well. Allow to cook until the onions are translucent and bit browned on the edges, about 5-6 minutes, stirring occasionally.
Add the mushrooms and a pinch of salt (salt helps to draw out the moisture in the mushrooms). Stir well together with the onions, and then allow the mushrooms to cook for about 3-4 minutes, undisturbed. Flip everything over to the other side and cook for another 3-4 minutes.
Add the garlic and stir well. Once you can smell the garlic, deglaze with the wine, scraping up any bits from the bottom of the pan.
Add the miso, Braggs, mustard and veg stock, along with about 1/2 cup of water, and stir everything well together.
Add half the beans, no need to strain them. Stir well.
Allow everything to cook together for about another 5 minutes, adding additional water if needed if the pan gets a bit dry.
While this is cooking, add the second half of the beans (along with the liquid) to a blender and blend well to form a kind of creamy sauce. Add this to the pan as well. Allow to cook for an additional 5 minutes.
Taste for seasoning and add salt if needed , as well as a nice healthy grind of fresh pepper.
Add spinach and parmesan and stir well to melt the cheese and wilt the spinach.
Serve with crusty bread.