Preheat oven to 400 degrees. Place flour, butter, 2 teaspoons sugar, salt, and baking powder in a 9-by-13-inch baking dish. Cut ingredients together until the mixture resembles cornmeal. With hands, press mixture onto bottom and sides of pan, evenly coating.
Arrange peaches evenly over top of crust. In a small bowl, combine the remaining 1/2 cup sugar and cinnamon and sprinkle over peaches.
Place in oven and bake for 10 minutes, or until crust begins to turn golden and sugar is bubbling.
Meanwhile, in a medium bowl, combine heavy cream and egg yolks. Remove kuchen from oven and pour cream-egg yolk mixture over peaches. Lower oven temperature to 350 and bake kuchen 20-30 minutes more, until custard mixture is set. Allow to cool slightly, then cut. Serve warm.