In a large saucepan, heat olive oil and butter over medium heat until melted. Add onion and sauté for 4-5 minutes until soft. Stir in garlic and cook for another minute.

Add Arborio rice to the saucepan, stirring to coat with oil and butter. Toast for 1-2 minutes until edges turn translucent.

Pour in dry white wine or chicken broth and stir until absorbed, about 2-3 minutes.

Gradually add warm chicken broth, one ladle at a time, stirring constantly. Cook for approximately 18-20 minutes until creamy and al dente.

Stir in cooked shredded chicken and chopped sun-dried tomatoes. Cook for an additional 3-5 minutes.

Gently fold in fresh spinach and let wilt for a minute. Stir in grated Parmesan until melted. Season with salt, black pepper, and red pepper flakes.

Remove from heat, let sit for a moment. Spoon into bowls and garnish with chopped basil or parsley. Serve immediately.