Cut your chicken breasts in half lengthwise to make four thinner cutlets. Season them with salt & pepper (go fairly easy on the salt as pancetta is quite salty).
Add the olive oil to a skillet over medium-high heat.
Once the pan is hot, add the pancetta and fry until crispy (about 8-10 min). Transfer the pancetta to a plate, and leave the fat in the pan.
Add the chicken to the skillet and cook it for 4-5 minutes/side until golden. Transfer the chicken to a plate (same plate as the pancetta is fine).
Add the butter to the skillet. Let it melt, then add in the mushrooms. Cook the mushrooms, stirring occasionally, until the water has been released, it cooks off, and they get nicely browned.
Add the garlic, Italian seasoning, and white wine to the skillet. Let it bubble until the liquid is reduced by half.
In a small bowl, mix the cornstarch with 2 teaspoons of cold water and stir until dissolved.
Reduce the heat to medium. Add the cream and cornstarch slurry to the pan and give it a good stir.
Add the chicken and pancetta back to the skillet. Simmer for another 5 minutes or until the chicken is cooked through and the sauce has thickened a bit. If the sauce becomes too thick, add in another splash of cream of wine. Season with salt & pepper if needed and sprinkle with parsley if desired.