1. Heat the butter and olive oil in a large heavy based frying pan and gently fry the leeks till it is translucent.
2. Season the chicken breasts with salt and pepper and add to the onions.
3. Cook stirring for 3 minutes and then add the garlic.
4. Cook for a further 2 minutes, then remove with a slotted spoon and keep to one side until needed.
5. Add the cream to the pan to deglaze it.
6. Add the feta and peppercorns and cook gently to reduce the sauce until it coats the back of a spoon.
7. Stir in the chicken and cook till the chicken is cooked through.
8. Stir in the herbs and remove from the heat.
9. You can either stir the sauce into the cooked pasta or serve it on top. Top with grated Parmesan cheese.
10. Serve with a salad of rocket, radicchio, paper thin red onions and capers, splashed with fresh lemon juice and extra virgin olive oil.
11. Options: The feta cheese and Parmesan can be replaced by adding 150g of blue cheese of your choice.