Season the chicken breasts with salt and pepper.
Using a sauté pan, over medium high heat, heat 3 tbsp. olive oil.
Place chicken in sauté pan and quickly fry, for about 3 minutes per side, until cooked but still juicy.
Remove from the pan and hold in a warm oven.
In the same sauté pan, add the olive oil and garlic and cook for one minute until the garlic is softened.
Add the mushrooms, chicken stock and white wine.
Simmer for a few minutes until the volume decreases by about half.
Add the chicken back to the pan, along with all the other ingredients, except the feta cheese.
Toss together until the butter has melted and the chicken is warmed through.
At the last minute toss in the feta cheese.
Serve over cooked pasta.
