01 - Heat the olive oil in a large pot over medium-high heat. Add the sausage, breaking it into bite-sized pieces, and cook until well-browned, about 7 minutes.
02 - While the sausage cooks, place 1 cup of the drained beans in a bowl. Add 1/2 cup chicken broth and mash together until mostly smooth to form a creamy mixture.
03 - Add the remaining whole beans to the pot with the browned sausage. Pour in the rest of the chicken broth and stir in the mashed bean mixture. Bring to a gentle boil, then reduce heat and simmer for 5 to 7 minutes to blend flavors.
04 - Remove the pot from heat and stir in the spinach until just wilted. Season with salt and black pepper to taste.
05 - Ladle the soup into bowls and garnish with grated Parmesan cheese and crushed red pepper flakes as desired.