Make batter: Preheat oven to 400°F. Grease a 9-inch springform pan. In a bowl, whisk together sugar, baking powder and salt. Add eggs, milk and vanilla and whisk until blended. Add flour and melted butter and stir with a rubber spatula just until smooth. Scrape batter into prepared pan, spreading evenly.
Make topping: Drain peach slices and pat dry. Arrange peaches in an even layer on top of batter. In a cup, stir together sugar and cinnamon; sprinkle mixture onto peaches.
Bake cake until springy to touch, about 30 minutes. Meanwhile, beat egg yolk and cream with a fork. Drizzle mixture onto cake and bake until center is cooked through, 10 minutes longer. Let cake cool for 10 minutes on a rack. Remove springform. Serve warm.