Peaches and raspberries lend a double dose of seasonal flavor to this spoonable dessert from the French countryside. The eggy batter becomes custardlike when baked, so every bite is rich and creamy.
Butter a 12-inch round baking dish; set aside. Bring Lillet, 1 1/2 cups water, 3/4 cup sugar, and the vanilla bean and seeds to a boil in a large, wide saucepan over high heat, stirring until sugar has dissolved. Add peaches, cut side down, and cover with a round of parchment paper, placing it directly on top of peaches. Reduce heat to medium. Simmer until peaches are very tender, about 15 minutes. Remove from heat; let stand 30 minutes.
Preheat oven to 325 degrees. Using a slotted spoon, transfer peaches, cut side up, to prepared dish; reserve 1/4 cup poaching liquid (discard the vanilla bean). Arrange raspberries among peaches.
Whisk eggs, remaining 1/2 cup sugar, and the salt in a medium bowl. Gradually whisk in flour. Whisk in milk, melted butter, vanilla extract, orange zest, and reserved poaching liquid. Pour around fruit.
Bake until edges are puffed and golden, 40 to 45 minutes. Let cool on a wire rack 20 minutes before serving.
Clafouti can be refrigerated covered, up to 1 day.