Heat olive oil in a large pot or Dutch oven over medium heat.
Add the sliced Italian turkey sausage and cook until browned on all sides, about 5-7 minutes. Remove sausage from the pot and set aside.
In the same pot, add diced onion, carrots, and celery. Cook, stirring occasionally, until vegetables are softened, about 5 minutes.
Add minced garlic and cook for 1 minute until fragrant.
Stir in the dried lentils, diced tomatoes with their juices, chicken broth, dried rosemary, dried thyme, smoked paprika, red pepper flakes, salt, and black pepper.
Return the browned sausage to the pot and stir to combine.
Bring the mixture to a boil, then reduce heat to low and cover the pot.
Simmer gently for 25-30 minutes, or until the lentils are tender and most of the liquid has been absorbed. Stir occasionally to prevent sticking.
Once lentils are cooked, stir in the fresh baby spinach and cook for 2-3 minutes until wilted.
Taste and adjust seasoning with additional salt and pepper if needed.
Remove from heat and sprinkle chopped fresh parsley over the top before serving.