Arrange the sea bass fillet in the center of a baking pan just large enough to hold the fish. With the point of a sharp knife, make several slits in the top of the fillet. Insert a slice of garlic into each slit. Pour the wine and stock over the fish and season generously with salt and pepper.
Heat the oil in a small nonstick skillet over medium heat and sauté the onion slices until they begin to caramelize, about 5 minutes. Arrange them on top of the sea bass. Put the sliced tomatoes and eggplant in the skillet and sauté until lightly browned and soft. Arrange the tomato and eggplant slices alternately over the fish, overlapping slightly. Arrange the rosemary, thyme, bay leaves, and basil on top. Bake until the fish is white and flaky, about 25 minutes.
To serve, slice the sea bass and arrange on individual plates with tomato and eggplant slices on the side. Spoon the pan juices over the fish.