Heat oil in a large pot over medium-high heat. Add sausage and garlic and sauté until sausage is lightly browned, about 8 minutes. Add escarole and toss until wilted, about 5 minutes. Add stock and cannellini with their juices. Simmer until flavors blend and soup thickens slightly, about 20 minutes. Season to taste with salt and pepper. Ladle soup into bowls. Serve with Parmesan cheese. Portion into pint containers for made ahead lunch and dinners.