Heat oven to 350 degrees. Lightly butter an 8×8 or 9×9 round or square dish or pie plate.
Mix together the milk, 1/3 cup granulated sugar, eggs, vanilla, salt and flour in a large bowl.
Grease the pan with plenty of butter (I often melt the butter for a few minutes by putting it in the baking dish in the oven, and then making sure it covers the whole surface.) Pour a 1/4-inch layer of batter in the baking dish.
Spread the fruit over the batter and sprinkle on the remaining 1/3 cup granulated sugar. Pour on the rest of the batter and smooth with the a butter knife. Place in the center of the oven and bake about 45-50 minutes, until top is puffed and browned and a tester plunged into its center comes out clean. It will sink a little bit in the center as it cools.
If desired, sprinkle with powdered sugar just before serving. (Clafoutis should be served warm but not hot).