Instructions

Make the filling

• Combine the ricotta, Grana Padano, nutmeg, and 1/4 tsp. salt in a medium bowl. Transfer to a pastry bag fit with a 1/2-inch plain round tip or cut off the end of the pastry bag or one of the bottom corners of a zip-top bag to make a 1/2-inch opening. Refrigerate until ready to use.

Make the pasta dough

• In a medium bowl, combine the flour with a pinch of salt. Pile the flour into a mound in the center of a clean work surface, and make a well in the center. Crack the eggs into the well, and begin stirring with a fork, gradually incorporating the flour from the center of the well and working outward, using a bench scraper as necessary to push the flour together and keep the walls intact.
• When the dough forms a ball and becomes too firm to stir, lightly flour your hands, and begin kneading, folding and pressing the dough over itself continuously, until dough is smooth and elastic, 10 to 15 minutes. Form the dough into a ball and wrap in plastic wrap. Let rest 1 hour at room temperature. In the meantime, make the sauce.

Make the sauce

• In a medium Dutch oven or other heavy-duty pot, heat the oil over medium-high heat until shimmering. Add the carrots, and the onions, 1/2 tsp. salt, and 1/4 tsp. pepper. Cook until the vegetables soften, about 8 minutes. Add the tomato purée, and bring to a boil over high heat, then reduce to a simmer. Cook uncovered, stirring occasionally, until the sauce is slightly reduced, about 20 minutes. Whisk in the butter one cube at a time until it melts into the sauce. Adjust the seasoning to taste with salt and pepper. Set aside, covered, to keep warm.

Shape, fill, and cook the tortelloni

• Dust a parchment-lined baking sheet with flour and set aside. Cut the ball of pasta dough into quarters, remove one piece, and cover the rest with plastic to prevent drying.
• On a lightly floured surface, roll out the first piece of dough to about 1/4-inch thickness, and trim the rolled dough into strips so that it can be processed through a pasta machine.
• Work with one strip of dough at a time, keeping the others covered with plastic. Pass it through each consecutive setting on the pasta machine twice, beginning with 1 and ending with 4.
• Lay the rolled pasta sheet on the work surface, and cut it into 2-1/2 x 2-1/2-inch squares.
• Pipe about 1 tsp. of the filling into center of each square, and moisten the edges with water. Then fold in half on the diagonal to create a triangle. Gently but firmly, press to seal, expelling any air from the pocket. Bring the two opposite tips of the base of the triangle to meet, and pinch to seal. Repeat with the remaining squares. Transfer to the prepared baking sheet, cover loosely with plastic wrap, and refrigerate until ready to cook.
• Meanwhile, bring a large pot of well-salted water to a boil. Gently drop the tortelloni into the water, and cook until al dente, 2 to 3 minutes. Reserve about 1 cup of the cooking water and drain the tortelloni.
  Toss the tortelloni with enough of the tomato sauce just to coat, adding some of the cooking water if necessary to loosen the sauce. Transfer to warm bowls, and garnish with a drizzle of olive oil, basil leaves, and grated cheese. Serve immediately.