Combine wine, broth, prunes, brown sugar, vinegar, olives, garlic, oil and oregano in a saucepan and bring to a simmer over medium heat. Reduce the heat and simmer gently, uncovered, for 10 minutes. Season to taste with salt and pepper.
Place chicken breasts in a large shallow baking dish. Pour the sauce over the chicken, turning to coat. Scatter capers over the top. Bake until the chicken is no longer pink in the center, 30 to 35 minutes.
We have been making this recipe ever since we saw it in the 1996 Eating Well. It is great for a casual dinner party and every bit as good as the original Silver Palate recipe, which had loads of fat. And no one notices the prunes!