Bring a pot of water to a boil and cook the rigatoni to al dente.
Meanwhile, dice and sauté the chicken and dice then set aside, approximately 5-7 minutes.
In the same pan on a low flame, add in the shallot, garlic, butter and sauté until fragrant, 2 minutes.
To the garlic and shallot, add in the tomato paste and stir until combined. Add in the heavy cream, tomato sauce and let thicken.
Add back in the chicken, and wilt the spinach.
Pour in the cooked pasta and toss to coat.
Last, top with shredded mozzarella and cover for 10-15m to let the cheese melt into the pasta.
Notes
Save a little bit of the pasta water to add to the sauce as it'll give the sauce a richer, thicker flavor. The starch from the pasta helps with thickening!