In a small bowl mix together the mustard, honey, Worcestershire sauce and paprika.
Put one chicken breast in a freezer / sandwich bag and using a mallet or heavy object, firmly bash until it is about 1cm thick. Repeat with the second chicken breast.
Put half the marinade in with both pieces of chicken and mix until the chicken is covered. Leave in the fridge or cool box for about 1 hour.
Mix the sour cream / crème fraiche with the remaining marinade and keep to one side. Heat a large frying pan or cooking surface you are using and add a little oil.
Fry the chicken on a low heat for 3-4 minutes each side or until cooked through.
Pour the reserved cream and marinade mix into the pan and turn the heat up, let the sauce bubble up and once it starts to thicken turn off the heat and serve immediately.