Fresh Peach Cake

1/2 cup butter
1 1/2 cups firmly packed brown sugar
1 egg
2 cups all-purpose flour
1 teaspoon baking soda
Dash of salt
1 cup buttermilk
4 peaches, peeled and diced
1/4 cup granulated sugar
1 teaspoon cinnamon

Cream butter with brown sugar until light and fluffy. Beat in egg. Sift flour with baking soda and salt; add to creamed mixture alternately with buttermilk, beating until smooth after each addition. Gently blend in peaches. Pour batter into a greased 13 x 9-inch pan. Sprinkle sugar and cinnamon over top. Bake at 350 degrees F for 30 to 35 minutes or until done.