Combine butter sugars and eggs, then add molasses; beating thoroughly. Peel and chop peaches and stir into mixture. Combine remaining ingredients and stir into creamed mixture until smooth. Pour into greased and floured 9 inch square pan. Bake at 350°F for 40 to 50 minutes or until pick inserted into center comes out dry. Cut into squares and top with whipped cream and peach slices if desired.