Boil the half pound of pasta in salted water according to package directions. Remember to save some pasta water right before draining and set aside.

Drain the pasta in a colander and rinse very well with cold water to prevent it from becoming mushy.

Set the same large pot you boiled the pasta in on the stove over medium heat. Add 2 tablespoons of the butter and the diced onion. Cook 3 to 4 minutes.

Add the garlic, spinach, kosher salt, pepper, and crushed red pepper flakes. Cook 3 to 4 more minutes and remove from the pot.

Set the same pot, still over medium heat, and add the remaining 2 tablespoons of butter, heavy cream, Italian seasoning, kosher salt, pepper, and crushed red pepper flakes.

Bring to a boil and then reduce the heat to simmer for 5 to 7 minutes stirring a few times. Stir in the parmesan cheese during the last minute.

Note: Carefully watch as the cream comes to a boil, remove from heat for a moment if it bubbles up too much and continue stirring until it reaches a gentle simmer.

Stir in the shredded chicken, sun dried tomatoes, chicken base if using, the cooked pasta, the reserved pasta water that was set aside earlier, and cooked spinach.

Taste for seasoning and add more kosher salt, pepper, crushed red pepper flakes, and/or Italian seasoning if needed. Transfer to a casserole dish, top with the mozzarella cheese, and bake in a 375 degree oven for 20 to 25 minutes.

Garnish with parsley when serving desired.