Place the chicken breasts in a plastic bag, and using a rolling pin firmly hit them until they flatten to approximately ¼ - ½ inch in thickness. Cut each breast in half so you have a total of 4 pieces.
In a bowl combine the almond flour, salt and pepper and coat each of the pieces of chicken in the mixture.
Heat the oil in a frying pan and cook the chicken on medium high heat until golden brown on both sides. Remove and set aside.
Fry the garlic and pancetta, leeks, onion and mushrooms until softened. Add in the chicken stock and vinegar and deglaze the pan, scraping the sides to loosen any of the brown bits. Leave to simmer for 4-5 minutes until the liquid begins to reduce.
Return the chicken to the pan, reduce the heat to medium and allow to simmer for 6 more minutes until most of the liquid has evaporated. Sprinkle with chopped parsley before serving.
Notes
*Use white wine if you don't have white wine vinegar