Melt 1/4 cup butter; pour into an ungreased 9-in. round baking pan. Sprinkle with brown sugar. Arrange the peach slices in a single layer over the sugar.
In a large bowl, mix the sugar and remaining butter until light and fluffy. Beat in egg and vanilla.
Combine the flour, baking powder, and salt. Add flour mixture to the sugar mixture alternately with milk, beating well after each addition.
Spoon the batter over the peaches.
Bake at 350° for 45-50 minutes or until a toothpick inserted in the center comes out clean.
Cool for 10 minutes before inverting onto a serving plate. Serve warm with ice cream or whipped cream.