Butterfly chicken fillets and cut into two evenly sized mini steaks. Place chicken into a large mixing bowl and add the marinade ingredients. Mix thouroughly to coat evenly and leave to marinate for about 1/2 an hour.
Cook chicken in a pan over medium heat until browned and cooked through.
Place chicken on a plate to rest and cover with foil while you make the sauce.
Using the same pan the chicken was cooked in reheat over medium heat and add the shallot or small onion, cook until translucent.
Add the Thyme, mustard, cream and lemon juice.
Stir the cornflour mixture through until the sauce has thickened slightly. Take the pan off the heat.