1. Prepare the pasta frolla short-bread crust by placing the flour onto a firm, smooth work surface, or into a large bowl.
Add the sugar and pane angeli or baking powder, and mix.
3. Gather the dry ingredients into a mound and form a well in the middle.
4. Add the egg, cubes of butter and lemon zest, and working quickly with your fingers, work the wet ingredients into the flour mixture.
5. Mix by hand until the dough forms a homogenous, smooth ball. Cover in plastic wrap and refrigerate for at least 1 hour.
6. Preheat the oven to 350° F (180° C), and butter and flour a 9-11 inch or 26-28 cm. fluted-edge tart pan. If you cannot find a tart pan, a round spring-form pan or a pie plate, will also work, although it is helpful to have a pan with a removable bottom.
7. Take ⅓ of the dough and set it aside. You will use this later for the lattice on top. Roll out the remaining ⅔ of the pasta frolla and lay it into the tart pan, pressing the bottom and sides tightly against the edges. Spread the Nutella smoothly onto the crust.
8. Roll out the remaining dough, and cut strips that are about ½? or 1 cm. wide. You can use a fluted pastry cutter to make pretty edges if you have one. I was cooking in my mom’s kitchen and did not have mine with me, and as you can see straight edges work just fine, too. Arrange the strips of dough on top of the crostata in a lattice pattern, and pinch the edges together.
9. Bake for approximately 45 minutes, or until the crust is golden brown. Take care to not burn the Nutella. Let cool, and enjoy.