Bring a large of of water to a boil. Season with salt and add pasta. Cook until done about 10-12 minutes. Drain.
In a large skillet over medium high heat, pour in olive oil and allow to heat up 1-2 minutes. Place chicken thighs in the skillet and brown on both sides 3-4 minutes each side.
Remove the browned chicken from the skillet to a clean plate. To the skillet add the onion and garlic. Saute for 2-3 minutes until fragrant and translucent.
To the onion and garlic add the can of Italian tomatoes and heavy cream, stir to combine. Bring to a simmer and add the fresh spinach, stir to coat the spinach in the tomato cream sauce.
Place the chicken back in the skillet and bring the sauce up to a simmer. Allow to simmer, stirring occasionally, until the chicken has cooked through (165ºF) and the sauce has thickened about 15-20 minutes.