Make the pasta frolla (shortcrust pastry): In the bowl of a food processor, combine the flour, sugar, baking powder, and salt. Pulse to combine. Add the butter and pulse until the mixture resembles coarse sand. Whisk together the egg yolk, vanilla, and milk, then add to the bowl. Pulse until the dough comes together into a ball. When properly mixed, the dough will be crumbly but should hold together when squeezed. Refrigerate for 2 hours or until ready to use.

Make the ricotta filling: In a small saucepan, bring the water to a boil. Slowly add the semolina flour, whisking as you go. Turn the heat down to a simmer and cook for about 3–4 minutes, stirring frequently. Add a little more water if the mixture becomes too thick. It should have the texture of Cream of Wheat. Set aside and let cool completely before proceeding.

Using a large whisk or an electric mixer, combine the cooked semolina with the remaining filling ingredients. Refrigerate until ready to use.

Assemble the pastries: You are essentially making large ravioli. On a lightly floured surface, roll out the pasta frolla to a 1/16-inch thickness, shaping it into a rough rectangle about 12 inches wide and 6 inches tall. Place 3 large dollops of the filling evenly spaced across the bottom half of the dough. Fold the dough toward you and crimp to seal the pastry around each mound of filling. Cut out each pastry with a pastry cutter, large ring mold, or a wide glass. Each pastry should be roughly 3–4 inches in diameter. Place them on a baking sheet lined with parchment paper and refrigerate until ready to bake.

Final step: Preheat the oven to 350°F. Whisk together the egg and milk, then brush the top of each pastry. Bake for 18–20 minutes, or until golden brown. Serve warm or at room temperature.