In a bowl, coat the chicken with olive oil, tomato paste and all the seasonings. Heat a pan over medium-low heat and cook the chicken for 5–6 minutes on each side until it turns a deep red colour with lightly charred edges. Remove and set aside.
In the same pan, melt the butter. Add the seasonings and let them sizzle for 30 seconds. Pour in the double cream, stir well and simmer for 1 minute. Add the parmesan and stir until melted, smooth and creamy.
Serve the chicken over mashed potatoes and spoon the sauce generously over the top. Finish with fresh chives.