Preheat your oven to 350°F (175°C). In a 9-inch round cake pan, pour the melted butter and sprinkle the brown sugar evenly over it to create a caramel base.
Arrange the drained sliced peaches on top of the brown sugar mixture in a circular pattern. Sprinkle cinnamon over the peaches.
In a mixing bowl, whisk together the flour, baking powder, and salt.
In another large bowl, beat the softened butter and granulated sugar until light and fluffy, about 3-5 minutes.
Add the egg yolks to the butter and sugar mixture, mixing until well combined. Stir in the milk and vanilla extract until smooth.
Gradually add the dry ingredients to the wet mixture, stirring until just combined. Do not overmix; a few lumps are fine.
In a clean bowl, beat the egg whites with cream of tartar until stiff peaks form. Gently fold the whipped egg whites into the cake batter to create a light texture.
Carefully pour the batter over the peaches in the cake pan, spreading evenly.
Bake in the preheated oven for 30-35 minutes or until a toothpick inserted in the center comes out clean and the top is golden brown.
Remove the cake from the oven and cool in the pan for 10 minutes. Then invert the cake onto a serving plate so the peaches are on top.
Allow the cake to cool slightly before slicing. Serve warm, optionally with vanilla ice cream or whipped cream.