2) Season the chicken breasts with salt and pepper on both sides, reduce the heat to medium, and then place them in the pan (there should still be some butter and oil in the pan; if not, add a little more). Cook the chicken over medium heat for 3 to 4 minutes on each side.
3) Add the wine, followed by the chicken broth, shallot and garlic; cook for another 6 to 8 minutes or until the chicken is fully cooked through. Remove the chicken and set it aside on a plate.
4) Add the cream, mustard, lemon juice and herbes de Provence to the pan and stir to combine. Remove he pan from the heat.
5) Peel the shells from the prawns. Transfer the prawns to a bowl. Return the sauce to the heat, bring to a boil, and simmer until thickened slightly, about 2 to 3 minutes. Return the chicken and the prawns to the pan and reheat for 1 to 2 minutes. Sprinkle in the pistachios and then divide among 4 plates.