- Preheat oven to 375°F (190°C).
- For ratatouille, toss all vegetables with olive oil, thyme, oregano, garlic and salt and pepper in a baking dish. Bake covered for 10 minutes, then remove cover and bake about 20 minutes more, stirring occasionally, until all vegetables are fork-tender. Stir in lemon juice, olives and season to taste. Cover to keep warm.
- For chicken, keep oven at 375°F. Purée onion, herbs, 2 tbsp oil, lemon juice and a bit of salt and pepper in a food processor. Heat an oven-proof sauté pan over medium high heat and add remaining 2 tbsp oil. Add chicken breasts and cook for 2 minutes to brown. Turn chicken over to cook 2 minutes more. Spread onion-herb mixture over chicken and place pan in oven to cook chicken completely, about 15 minutes.
- To serve, place a spoonful of winter ratatouille in centre of plate. Slice each chicken breast into 6 slices, fanning around vegetables. Sprinkle chicken lightly with salt and pepper. Spoon excess onion-herb mixture over chicken and serve.