Horizontally slice each chicken breast right through the centre to create 4 even-sized breasts. In a large shallow dish, combine the flour with 1 tsp salt & ½ tsp garlic powder & black pepper. Individually dredge each breast through the flour then place to one side.
Heat 1 tbsp oil & butter in a large pan over medium-high heat. Add the chicken and fry both sides until golden on the outside and just about cooked through the centre (~3 mins each side). Remove from the pan & place on a plate to one side, then lower the heat to medium.
Melt in the remaining butter then add the shallots. Fry until soft & golden then add the garlic and lemon zest and fry for 30 seconds or so. Stir in the stock & cream then add the mustard, lemon juice and seasoning. I typically go for around 1 ½ tbsp lemon juice, but you can start with less and work up if you’d prefer.
Give it a good stir then gently simmer until the sauce begins thickening. Stir in the resting juices from the chicken, then add the chicken back to the pan. Baste in the sauce to coat and warm it back through, then serve with lemon slices and fresh parsley.
