Spinach and Sausage Lentil Soup

1 lb spicy pork sausage
1/2 medium red onion, diced
1 cup dried brown lentils, rinsed
1 can (15 oz) cannellini beans, drained and rinsed
1 carton (32 oz) chicken stock, plus one more cup
1 cup water
1/2 tsp caraway seed
1 tsp dried Italian spice
1/2 tsp garlic powder
1/2 tsp paprika
salt and pepper to taste
1 can (14 1/2 oz) fire-roasted diced tomatoes, undrained
6 cups fresh spinach

In dutch oven cook and crumble sausage and onion over medium heat until no longer pink, drain fat. Stir in lentils, beans, stock, water and spices, mix well. Bring to simmer, reduce heat, cover and cook until lentils are tender, about 30 minutes. Stir in tomatoes and cook another 5 minutes. Remove from heat and stir in spinach until wilted. Adjust seasoning as desired.