Peel and cut the onions into 1/4 inch slices.
In a heavy bottomed pot, add the butter and olive oil and let them heat up over medium heat.
Add the onions and salt and let them caramelise over medium heat, mixing every now and then. If you feel like you need to, add a little bit of wine or stock to deglaze as you mix. When the onions become soft and start to brown, add the garlic and mix well.
Add the balsamic vinegar, Worcestershire sauce, and white wine and deglaze the pot well.
Drain the canned beans.
Add the pepper, oregano, thyme, bay, beans, and stock and let it boil for 20 minutes.
Serve and garnish with your favourite homemade or store-bought croutons and some grated cheese.