Boil a large, salted pot of water for your pasta and cook it al dente according to package instructions.
Meanwhile, cut the chicken in half lengthwise so you've got 4 thinner pieces. Season both sides of each piece with the garlic powder and salt & pepper.
Add the butter and olive oil to a skillet over medium-high heat. Let the pan heat up for a few minutes, then cook the chicken for about 5 minutes per side or until cooked through; transfer to a plate.
Add the minced garlic to the skillet and cook for 30 seconds.
Stir in the tomato paste, tomato sauce, heavy cream, and Italian seasoning until smooth. Reduce heat to medium and let the sauce gently bubble for 3-5 minutes to thicken.
Cut the cooked chicken into strips.
Season the sauce with salt & pepper, then add the chicken strips and spinach; let warm through for 1-2 minutes.
If sauce thickens too much, add a splash of reserved hot pasta water.
Drain the pasta and return it to the pot. Pour the sauce with chicken and spinach over the pasta and toss to coat.
Serve immediately with freshly grated parmesan cheese on top.
