Step 1Cut shallow "'X" in bottom of each peach and carefully immerse in large pot of boiling water. After 15 seconds, remove 1 and try to pull peel back. If it comes away easily, remove peaches and rinse under cold water before peeling. Cut peaches in half and remove pits. Cut into slices. Toss with sugar and let rest at room temperature 1 hour.
Step 1Generously grease 6 (2/3-cup) souffle dishes or custard cups. Lightly coat each with flour, tapping out excess. Set aside on baking sheet.
Step 2Sift 2/3 cup flour, baking soda and salt. Set aside.
Step 3Peel peaches, cut in half and remove pits. Place 1 1/2 peaches in food processor fitted with metal blade; puree. You should have about 3/4 to 1 cup. Add butter, sugar, egg and vanilla. Process until smooth. Spoon sour cream in circle on batter; spoon dry ingredients over. Pulse until just mixed; it's OK if a little flour remains on surface.
Step 4Ladle 1/4 cup batter into each prepared dish. Cut remaining peaches into very thin slices. Arrange slices, overlapping, on batter, dividing evenly. Spoon remaining batter over, dividing evenly.
Step 5Bake at 350 degrees until browned and a toothpick inserted into center comes out moist but not gooey, about 30 to 32 minutes. Cool slightly on wire rack. Invert on dessert plates. (Can be baked a day ahead, completely cooled and refrigerated, covered airtight. Let come to room temperature before reheating. To serve, reheat cakes, uncovered, in 225-degree oven 15 minutes.)
Step 6Top with Sliced Peach Topping and juices, dividing evenly. Serve immediately.