Warm up the mash potato and keep warm aside.
Heat the oil and half of butter in a sauté pan over a medium/ high heat, drizzle a little oil and add the chicken pieces. Brown for 45-60 seconds until lightly coloured.
Next, add the onions and mushrooms and cook for 2-4 minutes until browned.
if using brandy, flambee the meat and vegetables by pouring the brandy carefully and then ignite.
When the flame dies down, add the stock, mustard, smoked paprika, salt and pepper.
Pour in enough cream at the stage.
Gently Scrape the base of the pan with a spatula to release all the bits that may have attached earlier and simmer for another 3-4 minutes until warmed through.
Remove from the heat and stir in the gherkins and herbs to just warm them through.
Check the seasoning and serve immediately with the mash potatoes, or alternatively with some rice depending on your preference.