1. Preheat oven to 350°F(175°C). Place bread cubes on a baking sheet and bake until dry and crisp, about 20 minutes. Place bread cubes in a food processor and pulse until ground into crumbs. Add olives, 2/3 of the garlic, and oil to the food processor. Pulse until well-blended.
2. Cut zucchini in half lengthwise and then into 1/4-inch thick slices. Wash the chanterelles well in cold water and remove the stems. Cut the chanterelles in half; reserve.
3 Grease the bottom of a baking dish with butter. Sprinkle shallots, half of the salt, half of the pepper, and remaining garlic into the baking dish. Add the wine, zucchini, and mushrooms. Cover the vegetables with a sheet of wax paper.
4. Season the salmon fillets with the remaining salt and remaining pepper. Pack the bread crumb mixture on top of the salmon fillets. Place the fillets on top of the wax paper. Bake until fish flakes easily with a fork, about 30 minutes. Transfer salmon to a plate; discard wax paper.
5. Stir basil into the zucchini mixture and adjust seasoning. Spoon stew onto plates and top with the salmon. Serve immediately.