Step 1

Slice chicken breasts lengthwise, salt and pepper and brown on both sides in olive oil on medium heat until golden. Remove to a plate. (At this point chicken will not be cooked all the way through.)

Step 2

To the same pan add the mushrooms together with chopped rosemary, salt and pepper and brown the mushrooms over medium heat for 2-3 minutes, add the chopped shallots and minced garlic and cook for 1-2 minutes longer. Add a heaped tablespoon of flour and stir to combine. Then add the white wine and scrape the bottom of the pan with a spatula to release the brown bits into the liquid. Pour in chicken stock, double/heavy cream, add 1 tbsp of mustard and stir to combine.

Step 3

Then add the chicken breasts together with the juices they released back to the pan, and bring the sauce to a boil, then lower the heat to low and let it simmer for 10 minutes. Taste the sauce and add more salt and pepper if necessary.