Cook the Pasta: Bring a large pot of salted water to a boil, add short pasta, and cook until al dente for about 8-10 minutes. Reserve 1 cup of pasta water, drain, and set aside.

Sauté the Chicken: Season chicken breasts with salt, pepper, and garlic powder. In a skillet, heat olive oil and butter, add chicken, cooking for 5-7 minutes on each side until golden brown and cooked through. Allow to rest and slice.

Make the Roux: In the same skillet, sprinkle all-purpose flour over drippings, stirring to form a roux. Cook for about 1 minute until light golden.

Deglaze with Chicken Broth: Gradually add chicken broth while stirring to deglaze the pan, simmering for 2-3 minutes until slightly thickened.

Create the Creamy Sauce: Stir in heavy cream, pesto, lemon juice, and sun-dried tomatoes, simmer and let thicken for about 3-5 minutes.

Incorporate the Spinach: Fold in fresh baby spinach and stir until wilted for about 1-2 minutes.

Combine Pasta and Sauce: Add cooked pasta to skillet, toss to coat, and add reserved pasta water to adjust the sauce's consistency as needed.

Serve and Garnish: Spoon pasta onto plates, top with sliced chicken, and sprinkle with grated Parmesan cheese if desired. Serve immediately.