In a heavy sauce pan or cast iron pot heat the olive oil over medium heat. When the oil is hot, it will shimmer, add the sausages to the pan and cook on all sides until golden brown. Remove the sausages to a plate and set aside while you make the bean casserole.
Add a drop more olive oil to the pan and add the diced onion, thyme and garlic, Saute until softened about 5 minutes. Once the onions are soft, pour in the white wine, chicken stock and butterbeans. Bring to a simmer for about 5 minutes to simmer off the alcohol.
Add the spinach, creme fraiche, lemon zest, most of the bread crumbs (save 2 tablespoons for topping) and parmesan cheese. Mix until smooth and creamy. Place the sausages back into the casserole.
Cover with a lid and cook for another 5 minutes to ensure the sausages are hot. Remove the lid, and top with the remaining bread crumbs, some extra parmesan, and a drizzle of olive oil. Divide between bowls and serve.