For the peaches:
Brush the bottom of a tight-sealing 10" spring-form cake pan with the butter. Sprinkle in the sugar and cinnamon. Toss the peach slices with the lemon juice. Arrange the peach slices in a spiral-like fashion on top of the sugar.
For the batter:
Preheat oven to 350 degrees F. Combine the first 6 ingredients in a bowl. Place the butter and brown sugar in a second bowl and beat until well combined. Mix in the eggs, and then the sour cream. Mix in the milk alternately with the flour mixture until a smooth batter is formed. Spoon the batter into the pan. Bake for 90 minutes, or until the cake springs back when gently touched in the center.
Cool the cake on a baking rack for 15 minutes. Run a paring knife around the outer edges of the pan. Set a cake plate over the pan; invert the pan to release the cake onto the plate. Serve warm or at room temperature with, if desired, a dollop of whipped cream.