Preheat oven to 350 F. Butter and flour a 9 inch round cake pan.
In a large mixer bowl, whisk together flour, sugar, baking powder, salt and nutmeg.
Add eggs, buttermilk and vanilla beat until smooth.
Add 1/2 cup butter, beat to combine. Set this batter aside.
Place the remaining 1/4 cup butter in your prepared pan. Set in oven to melt butter, about 2-3 minutes. Sprinkle brown sugar over melted butter. Top with sliced peaches, keep peaches in a single layer.
Spoon cake batter over peaches, smoothing top with an offset spatula.
Bake until a toothpick comes out clean when inserted in the center, about 40 to 50 minutes. Cover cake after 30 minutes of baking to prevent excess browning.
After removing cake from oven, run a knife around the edges of pan to loosen cake. Invert still hot cake onto a serving plate, let cool slightly. Serve warm.