Preheat oven to 350 degrees.
Melt butter in microwave or stovetop. In small bowl combine the melted butter, brown sugar, and cinnamon then pour in the bottom of a 9-inch cake pan.
Place peach slices on top of the brown sugar mixture in pan.
Whisk together the flour, baking powder and salt in a medium bowl.
In a separate large bowl, using electric mixer or stand mixer cream together the butter and sugar until light and fluffy. Then add in the vanilla and egg yolks and beat until combined.
Next slowly add in half the flour mixture to the creamed butter mixture and beat until combined. Pour in the milk and beat again. Then add the remaining flour mixture and mix until combined.
In a separate bowl, add the egg whites and cream of tartar. Beat on high speed until stiff. Once stiff add it to the batter and fold in just until combined.
Carefully pour the cake batter over the peaches in pan and spread evenly.
Bake in a preheated oven for 40 to 45 minutes, until a toothpick inserted into the center of the cake comes out clean.
Allow to cool for 10 minutes then run a butter knife around the edge of the pan to loosen the cake then place a serving plate over the cake and flip the cake pan. Carefully lift the baking pan away from plate.