Preheat oven to 350 degrees.

Combine the melted butter, brown sugar, and cinnamon. Pour the mixture in the bottom of a 9-inch cake pan.

Top the butter mixture with the sliced peaches.

In a medium bowl, whisk together the flour, baking powder, and salt.

In a separate bowl, beat together the butter and sugar until light and fluffy. Add the vanilla and egg yolks and beat until combined.

Add half the flour mixture to the butter mixture and beat until combined. Add the milk and beat again. Pour the remaining flour mixture into the bowl and mix until combined.

In a separate bowl, combine the egg whites and cream of tartar. Beat the mixture on high speed until stiff. Pour the mixture into the batter and fold in until just combined.

Pour the batter over the peaches and spread evenly, being careful not to disturb the peaches.

Bake in the preheated oven for 45 minutes, until a toothpick inserted into the center of the cake comes out clean.

Allow to cool slightly, then run a knife around the edge of the pan to loosen the cake. Flip the pan over onto a serving plate. Serve warm or at room temperature.