Brown the chicken: Heat the olive oil in a large Dutch oven or heavy-bottomed pot over medium-high heat. Add the ground chicken and cook for 6–8 minutes, breaking it into small crumbles with a wooden spoon, until fully cooked. Transfer to a plate.
Sauté the onion: Reduce the heat to medium. Add the butter and diced onion to the same pot. Cook for 3–4 minutes, stirring occasionally, until softened.
Add the aromatics: Stir in the garlic, sun-dried tomatoes, Italian seasoning, sweet paprika, salt, and black pepper. Cook for 1 minute, stirring frequently, until fragrant.
Add the flour: Sprinkle the flour over the onion mixture and stir well to coat. Cook for 1 minute, stirring constantly.
Pour in the broth: Gradually pour in the chicken broth, stirring continuously to prevent lumps. Scrape the bottom of the pot to release any browned bits.
Simmer the soup: Return the cooked ground chicken and any accumulated juices to the pot. Bring to a gentle simmer and cook uncovered for 8–10 minutes, stirring occasionally, until the broth thickens slightly.
Make it creamy: Reduce the heat to low. Stir in the heavy cream and freshly grated Parmesan cheese. Cook gently for 2–3 minutes, stirring until the cheese melts and the soup becomes smooth and creamy. Do not boil.
Add the spinach: Stir in the fresh spinach and cook for 1–2 minutes, just until wilted.
Remove the pot from the heat and stir in the fresh lemon juice. Taste and adjust the seasoning as needed.
Ladle the soup into bowls and garnish with additional Parmesan cheese and freshly cracked black pepper, if desired.