Preheat oven to 250 degrees F.
Core tomatoes, cut in half horizontally, and remove seeds. Sprinkle with salt and pepper. Place tomato halves cut side up on a rack in the oven and cook for 1 to 1 1/2 hours, or until shriveled and partially dried. Puree half the tomatoes in a blender until liquefied, then add remaining tomatoes, olive oil, salt, and pepper. Puree until smooth. (Thin with a few tablespoons water if sauce seems thick.) Strain to remove any seeds and skins, and set aside until serving time.
Preheat oven to 400 degrees F. Blanch garlic in a small pot of rapidly boiling, salted water for 1 minute. Drain and set aside to cool.
Create a pocket for stuffing by running your fingers between the skin and meat of each breast, leaving one side attached. Season all over with salt and pepper.
In a small bowl, combine chopped parsley and garlic. Divide into 6 equal parts and stuff each breast between skin and meat, spreading evenly. If necessary, tie skin to breasts to keep in place.
Heat chicken fat or oil in a large, ovenproof skillet over medium high heat. Saute chicken, skin side down first, until golden brown, about 2 minutes per side. Transfer to oven and bake about 10 to 15 minutes. Set aside for 5 minutes, to redistribute juices before serving.
Whisk tomato puree and coat 6 serving plates with it. Cut each breast into 1/2inch slices, across width. Arrange slices over puree and serve.
c.1997, M.S. Milliken & S. Feniger, all rights reserved