For the pie crust: Combine the flour, butter, sugar, milk, egg and baking powder in the bowl of a stand mixer fitted with the paddle attachment. Mix until well combined. The dough will look like really wet sand but when you pinch it between your fingers it should hold together.
Press the dough together in the bowl of the mixer until it forms a uniform ball. Knead it just a couple of times on a clean work surface to make it holds together well. Divide the dough in half. Set one half aside and divide the other in half again. Place the two quarters in two separate 9-inch pie plates and press the dough down and up onto the sides with your fingers, ensuring that it is even. Chill in the refrigerator for 20 minutes before filling. Set the remaining dough aside in the refrigerator for the topping.
Position a rack in the middle of the oven and preheat to 325 degrees F.
To make the pies: Divide the ricotta mixture evenly between the 2 pie shells. Pipe 1/4 cup of the chocolate-hazelnut spread in lines onto each pie and swirl with a knife or skewer to create perpendicular lines.
Remove the remaining dough from the refrigerator and break it into small pieces. Crumble them on top of each pie. It doesn't have to be pretty, it will look amazing after its baked no matter what. Bake until the pie is golden brown on top, 1 hour. Let rest for 20 to 30 minutes. Serve warm.