Preheat oven to 325°F. Generously butter shallow 1 1/2-quart glass or ceramic baking dish. Combine cherries, 1 tablespoon sugar and cornstarch in medium bowl; toss to coat. Arrange cherries in bottom of prepared dish. Blend flour and almonds in processor until nuts are finely chopped. Whisk eggs, salt and remaining 1/2 cup sugar in large bowl to blend. Whisk in flour mixture. Add milk, butter, lemon peel, and vanilla and almond extracts; whisk until smooth. Pour custard over cherries. Bake clafoutis until set in center and golden on top, about 55 minutes. Cool slightly. Sprinkle powdered sugar over and serve warm.