Tarta de Ricota con Dulce de Leche

Directions

1. Preheat the oven to 375 F (191 Celsius). For the sugar crust, grate cold butter through the largest holes into a large mixing bowl. Add both flours, salt, and sugar. Mix and knead with your hands to incorporate some of the butter so mixture is still a bit crumbly. Make a well in the center with your fist and pour milk and egg yolk. Fold it in with your hands and mix just enough to get rid of large clumps, but do not over knead or it will rend a tough crust! Form into a ball, wrap with plastic wrap, and freeze for 10 minutes.
2. For the ricotta filling, use a stand mixer or electric beater. Whip the egg whites for about 1 minute or until foam beings to form. Beat in the sugar for duration of a few minutes, until peaks begin to form and mixture is a bit glossy. Then mix the ricotta, egg yolks, and milk with a fork in a small separate bowl and set aside.
3. In another small bowl, stir the flour, salt, and baking powder. Add this dry mixture into the stiffened egg whites followed by the ricotta mixture. Fold in with a rubber spatula carefully until evenly incorporated. Be careful not to beat the air out of the egg whites too much.
4. Place the sugar crust ball in a 9 inch cake pan and begin to knead with your fists, spreading it out so as to cover the entirety of the bottom of the pan, but not the sides. Pour in the filling. Mix dulce de leche with lemon juice, dip it with a fork or knife and run through the filling in swirled motions. Bake for approximately 45 minutes until the center is firm but jiggly. Let it cool, then refrigerate, and serve it cold with powdered sugar on top if desired.