Place a rack in the middle of the oven and preheat to 425°F.
In a saucepan, sauté the apples in 2 tablespoons of olive oil. Cook, turning as needed, until tender, 5 to 7 minutes. Sprinkle evenly with brown sugar, lemon juice and cinnamon and stir. Remove from heat.
Oil a 9 x 13-inch baking dish with 1 tablespoon olive oil, tilting the dish to coat the bottom and sides. Place the apples in an even layer on the bottom of the dish. Add fresh raspberries.
In a bowl, whisk together eggs, milk, flour, vanilla and fleur de sel until smooth. Gently pour the mixture over the fruit.
Bake until puffed and golden, about 35 minutes. Remove from the oven. Using a fine-mesh sieve, sprinkle powdered sugar over the top. Serve immediately.
