This also may be made using skin on chicken pieces also such as legs and/or thighs, for the best flavor try to use a mixture of red and yellow teardrop tomatoes, this is not for anyone with a plain palette.
Season the chicken with salt and pepper, then brown on both sides (about 3-4 minutes on each side) remove to a large platter, cover with foil to keep warm (I put my plate in a 200 degree oven to stay warm).
To the same skillet, add in the mushrooms and saute until all of the liquid is absorbed (about 6-7 minutes).
Add in onions, garlic and dried chili flakes (if using) to the mushrooms and saute for about 3-4 minutes.
Add in the chicken broth; simmer for about 6 minutes or until most of the liquid is absorbed.
Add in the Kalamata olives, plum tomatoes and capers, season with salt and pepper; bring to a boil, then reduce heat and simmer for about 10 minutes or until the liquid is reduced by half.
Add in butter and stir until melted.
Mix in the small teardrop tomatoes; simmer for about 5 minutes (you can simmer a bit longer).