Heat olive oil in a large deep skillet or Dutch oven over medium-high heat.
Season chicken pieces with salt and black pepper.
Add chicken to the skillet and cook for 5-6 minutes until browned and cooked through, stirring occasionally. Remove chicken from skillet and set aside.
In the same skillet, add minced garlic and cook for 1 minute until fragrant.
Pour in chicken broth and heavy cream, stirring to combine.
Add broken fettuccine pasta, dried Italian seasoning, and crushed red pepper flakes to the skillet.
Bring the mixture to a boil, then reduce heat to medium-low and simmer uncovered for 12-15 minutes, stirring occasionally, until the pasta is tender and most of the liquid is absorbed.
Stir in the cooked chicken, grated Parmesan cheese, and chopped spinach.
Cook for an additional 2-3 minutes until the spinach wilts and the cheese melts, stirring gently to combine.
Remove from heat and let the pasta rest for 2 minutes before serving.