Cook the Pasta: Bring a large pot of salted water to a boil. Add short pasta and cook until al dente, about 8-10 minutes. Reserve 1/2 cup of pasta water before draining.

Prepare the Chicken: In a skillet, heat olive oil and butter. Season chicken with salt, pepper, and garlic powder. Cook for 6-7 minutes per side until golden brown and fully cooked. Remove, rest, and slice.

Make the Sauce Base: In the same skillet, add flour and stir for 1 minute to create a roux. Scrape browned bits for added flavor.

Add the Liquid Ingredients: Gradually pour in chicken broth and heavy cream, stirring constantly. Add pesto and lemon juice, simmer for 3-5 minutes until slightly thickened.

Incorporate Spinach and Tomatoes: Add spinach and sun-dried tomatoes, cook for 2-3 minutes until spinach wilts.

Combine Pasta and Sauce: Toss drained pasta into the skillet, mixing to coat. Add reserved pasta water for desired consistency.

Finish and Serve: Stir in sliced chicken and serve hot, garnished with Parmesan cheese if desired.