Pre-heat the oven to 400 degrees. Place the chicken breasts on a cutting board and if necessary, pound with a meat mallet to ensure an even thickness. Sprinkle each breast with salt, pepper and oregano on each side.
Pour 1 ½ teaspoons of olive oil into a large skillet and bring over medium-high heat. Place the breasts in the pan in a single layer and cook for 1-2 minutes on each side to lightly brown the outside of the chicken.
Mist a baking sheet with cooking spray and place the chicken breasts onto the sheet. Cover with aluminum foil and bake for 15 minutes.
While the chicken is baking, combine the balsamic vinegar, sugar and salt in a small saucepan and stir to combine. Bring to a boil over medium-high heat and then reduce the heat to medium low. Simmer for 10-15 minutes until the mixture has reduced and thickened and will coat the back of a spoon. Split the balsamic glaze into two small dishes.
When the chicken comes out of the oven, discard any extra liquid produced by the chicken. Use a pastry brush to brush the glaze from one of the dishes onto the chicken breasts. Place the baking sheet of chicken back in the oven, uncovered this time, for 5-10 minutes until the chicken is cooked through. Wash your pastry brush thoroughly.
Combine the chopped tomatoes, sliced basil, minced garlic and the remaining ½ teaspoon of olive oil in a bowl and add salt and pepper to taste. Stir to combine.
When the chicken breasts are done cooking, brush the second dish of balsamic glaze over the chicken breasts. Serve each breast topped with ¼ cup of the bruschetta tomato mixture.