Chicken Mozzarella Pasta

This is from Pioneer Woman's Dinnertime Cookbook.  It is good and makes excellent leftovers. 

2 tablespoons olive oil, more for drizzling 
2 boneless, skinless chicken breasts, cut into small pieces 
Kosher salt and black pepper to taste 
1 large onion, finely diced 
2 garlic cloves, minced 
One 25-ounce jar good-quality marinara sauce 
½ teaspoon red pepper flakes
2 tablespoons minced parsley 
1 pound penne, cooked to al dente and kept hot 
¼ cup Parmesan shavings, plus more for serving 
8 ounces (½ pound) fresh mozzarella, cubed 
12 basil leaves, cut into chiffonade 

Heat the olive oil in a large skillet over medium-high heat. Add the chicken, season it with salt and 
pepper, and cook for 2 minutes on the first side, until golden brown, then flip and cook for 2 minutes 
more, until totally done. Remove the chicken to a plate. 

Add the onion and garlic to the pan. 

Cook, stirring, for 3 to 4 minutes, or until the onions are golden brown.  

Reduce the heat to low and add the marinara sauce, red pepper flakes, and ½ cup water. 

Stir the sauce, then add the parsley and stir it through. Let the sauce simmer for 7 to 8
minutes more, stirring occasionally. 

Place the pasta on a large platter, drizzle on a little olive oil, and sprinkle on some Parmesan shavings. Throw the mozzarella into the piping-hot sauce ; stir it through, allowing the cheese to begin to soften and melt. 

Before the cheese fully melts, ladle the sauce onto the pasta.

Sprinkle on a bunch of basil at the end, then dig in! It’s a cheesy wonderland in there.