Heat the olive oil and butter in a large pot or Dutch oven over medium-high heat.

Season the chicken with salt, black pepper, and garlic powder, then add it to the pot. Cook for 4 to 5 minutes, stirring occasionally, until lightly browned and mostly cooked through. Remove the chicken to a plate.

Add the diced onion to the pot and cook for 3 to 4 minutes, stirring often, until softened. Stir in the minced garlic and cook for 30 seconds until fragrant.

Sprinkle the flour over the onions and garlic, stirring constantly for 1 minute to form a light roux.

Slowly pour in the chicken broth while stirring to prevent lumps. Add the sun-dried tomatoes, Italian seasoning, and red pepper flakes if using, then bring the soup to a gentle simmer.

Stir in the gnocchi and return the chicken and any accumulated juices to the pot. Simmer for 5 to 7 minutes, or until the gnocchi is tender and the chicken is fully cooked.

Reduce the heat to low and stir in the heavy cream, spinach, and Parmesan cheese. Cook for 1 to 2 minutes until the spinach wilts and the soup is creamy and well combined.

Taste and adjust seasoning with more salt and pepper if needed. Ladle into bowls and garnish with fresh basil and extra Parmesan before serving.