Heat the olive oil in a large heavy-bottomed saucepan over medium-high heat. When hot, add the chicken sausage and cook for 4-5 minutes until browned. Reduce the heat to medium and add the onion and garlic. Cook for 4-5 minutes until the onions are translucent and the garlic is fragrant. Stir in the tomato paste, paprika, oregano and chili flakes and cook for 3 minutes.Add the fresh spinach, and cook, stirring continuously until the leaves are completely wilted, about 3 minutes. Add the beans, crushed tomatoes and vegetable stock and bring to a boil. Lower to a simmer and cook, uncovered for 15 minutes. Season with salt and fresh ground pepper to taste. Ladle soup into bowls and top with freshly grated Parmesan if you like.