Preheat oven to 400: Halve tomatoes and place them, chopped onion, garlic, thyme leaves, salt and pepper in a pan, toss with olive to coat all. Bake 30 minutes or until tender, stir once. Bake until tender or done, cool slightly.
In a blender process tomato mixture and basil in small batches until blended. Transfer into a large saucepan and heat through. Garnish with croutons and a little fresh basil leaves if wanted. Serve