How to Make It
Combine the flour and semolina in a food processor and pulse to mix. With the machine on, add the eggs, egg yolks and olive oil and process until moist crumbs form. Turn the dough out onto a lightly floured work surface and knead until silky and smooth; knead in more flour if the dough is too sticky. Wrap the dough in plastic and refrigerate overnight.
Line a strainer with a coffee filter and spoon in the ricotta. Set the strainer in a bowl, cover and let drain overnight in the refrigerator.
Preheat the oven to 350°. Spread the almonds on a pie plate and toast for about 8 minutes, or until golden and fragrant. Let the nuts cool completely, then finely grind them in a food processor and transfer to a bowl.
Puree the drained ricotta in a food processor until creamy. Add to the ground almonds along with the Parmesan and season with salt and white pepper. Stir in the truffle puree and then the beaten egg. Transfer the filling to a pastry bag fitted with a 1/4-inch-round tip or to a sturdy plastic bag with a corner snipped off. Refrigerate the filling.
Cut the pasta dough into 6 pieces and let it return to room temperature. Using a hand-cranked pasta machine, roll 1 piece of dough through successively narrower settings to the thinnest setting. Lay the pasta sheet on a lightly floured work surface, sprinkle with flour and cover with a piece of wax paper. Repeat the process with the remaining pasta dough, dusting the sheets with flour and layering them between wax paper. Using a 2 1/4-inch round biscuit cutter, cut out rounds from each pasta sheet and cover with plastic wrap.
Pipe a scant 1/2 teaspoon of the filling in the center of a dough round. Fold the dough over the filling to form a half moon and press the edges to seal; lightly brush the dough with water if it becomes dry. Bring the corners of the half moon together around a finger, overlapping them slightly and pressing them together to secure. Fill and shape the remaining tortellini, transferring them to a tray lined with floured wax paper as they're shaped.
Bring a large pot of salted water to a boil. Add the tortellini and cook, stirring occasionally, until they rise to the surface and the pasta is cooked through, 7 to 8 minutes. Drain the tortellini and transfer to a large bowl.
In a saucepan, bring 2 tablespoons of water to a boil. Add the butter, shaking the pan to combine. Add a few dabs of truffle puree and season with salt. Add the sauce to the tortellini. Transfer the tortellini to warmed bowls, garnish with thyme sprigs and serve.
The intensity of flavor in truffle puree depends on the brand, so make sure to adjust the amount of puree according to taste. As an alternative to the truffle puree, Vetri recommends truffle oil, which also varies in intensity.