Base-Preheat oven to 375~. Lightly grease base of 10" springform pan. Beat whole egg in 1-1/2-qt bowl with mixer on high speed - 4 minutes - to a thick yellow foam. Mix in sugar on low speed until smooth. Add flour, water, vanilla, baking powder and salt. Mix on low speed until fully blended. Pour into springform pan, roll around until level. Bake 16 to 18 minutes on lowest oven rack. Cool to room temp. Filling-Preheat oven to 325~. Mix cream cheese, sugar, eggs and flour with electric mixer on high until smooth. Add vanilla, sour cream and peach flavoring and mix on medium until a smooth thick consistency is obtained. Fold in peach slices carefully - distribute evenly. Pour cheesecake filling onto cooled sponge cake base. Bake 70 minutes on lower oven rack, turn off oven, open oven door to broil position and let cake remain 40 minutes. Cool to refrigerated temperature. Topping-Top with fresh whipped cream or equivalent and serve. Store up to 2 days in the fridge.