Heat oven to 350 degrees.
Sift flour, baking powder and salt; set aside.
Add butter and sugar to the bowl of a large stand mixer (or use a hand mixer) and mix on medium speed until light yellow in color (a few minutes should do the trick).
Add the sifted ingredients to the bowl, mix gently, then add eggs and mix until just combined.
Transfer batter to an ungreased 9" spring-form pan and spread evenly.
Cover batter with peach slices (arrange however you wish). Sprinkle with the remaining tablespoon of sugar, lemon juice, and cinnamon.
Bake until a cake tester comes out clean in the center and the cake is golden, 45-50 minutes. Remove from oven and cool, then unmold from pan. Serve with whipped cream, creme fraiche, or more sliced peaches.