In a deep (12-14 inch) skillet or a large Dutch oven, heat the olive oil over medium-high heat. Add the pancetta and cook, stirring occasionally, until the pancetta is browned and crisp and the fat renders, about 7-8 minutes. Use a slotted spoon to remove the pancetta to a paper towel-lined plate, reserving the drippings in the pan.
Season the chicken on both sides with salt and pepper to taste. Cook the chicken in the pancetta drippings for about 2 minutes per side, or until cooked through and the meat reaches an internal temperature of 165°F. Remove to a cutting board.
To the same skillet, add the onion, garlic, rosemary, salt to taste, and red pepper flakes. Cover and sweat for about 2 minutes.
Add the broth, water, and tomatoes (with their juices); bring to a boil.
Reduce the heat so that the liquid is at a gentle boil, stir in the pasta, and cook until al dente, according to package directions. Stir the pasta occasionally as it cooks so that it doesn’t stick.
Slice the chicken into thin strips or into bite-size pieces.
Reduce the heat to low; stir in the cooked pancetta, the sliced chicken, and the spinach. Toss until the spinach leaves wilt.
Add the Parmesan cheese; stir to combine. Taste and season with additional salt and pepper, if necessary.
Spoon or ladle into bowls. Top individual servings with additional cheese and garnish with chopped fresh herbs, if desired.