How to Make It
In a food processor, pulse the flour a few times. Add the egg yolks, egg, milk and olive oil and process until a dough forms. Scrape the dough out onto a work surface and knead until smooth, about 2 minutes. Flatten the dough into a disk, wrap in plastic and let stand at room temperature for at least 30 minutes or for up to 2 hours.
Cut the dough into 4 equal pieces; work with 1 piece at a time and keep the rest wrapped. Flatten the dough with your hands and run it through successively narrower settings on a pasta machine until you reach the thinnest. Cut the pasta sheet into six 3 1/2-inch squares. Transfer the squares to a lightly floured baking sheet and cover with plastic wrap. Repeat with the remaining pasta dough.
Lay a pasta square on the work surface. Set a piece of cheese 1/3 inch from the bottom edge; fold the top of the square over the cheese to make a neat rectangle. Press lightly all around the filling to release any air. Repeat with the remaining pasta and cheese. Using a fluted pastry cutter, trim the ravioli edges to seal them. Transfer the ravioli to a lightly floured baking sheet, cover with plastic wrap and refrigerate for up to 3 hours.
Bring a large saucepan of water to a boil. Salt the water generously, add the ravioli and boil just until al dente.
Meanwhile, melt the butter in a large skillet and add the orange zest. In a colander, drain the ravioli, allowing a little of the cooking water to remain so they don't stick. Add the ravioli to the skillet and gently toss with the butter to coat. Transfer the ravioli to shallow bowls. Season with pepper and garnish with a little grated Pecorino. Serve at once.