Fresh mushroom tortellini

Method

1. For the pasta, put the flour and salt in a food processor, then add the egg, yolks and 2 tbsp cold water. Pulse the mixture to form clumps of dough, then turn out onto a clean work surface. If you don’t have a food processor, sift the flour onto a clean work surface, make a ring of flour, then put the eggs and salt in the centre. Using your fingers pinched together, gradually bring in the flour in a pecking motion. Add the water and work in to form a dough using your hands to bring it together.
2. Knead the dough for 15 minutes or so until smooth, elastic and hard to knead – it should be quite stiff. Wrap in cling film and rest in a cool place (not the fridge) for 30 minutes at least and a maximum of 2 hours.
3. Meanwhile, prepare the filling. Soak the dried porcini in 140ml freshly boiled water for 10 minutes. Heat a frying pan over a medium heat with a glug of oil and fry the onion for 8 minutes or until it softens and colours a bit. Add the garlic and fry for 2 minutes. Meanwhile, drain and finely chop the porcini (discard the soaking water), then add to the pan. Turn up the heat and fry both types of mushrooms until they start to colour. Turn off the heat and cool. Stir in the mascarpone, taste and season.
4. Once the pasta has rested, dust the work surface with flour, then divide the dough into 4 equal pieces and wrap 3 of them in cling film. Flatten the other piece with your hands, then dust the pasta machine rollers with flour. Starting with the widest setting on the pasta machine, roll the pasta through a few times until smooth. In between each roll-through, fold the pasta in half so it fits into the machine and to help with the texture. Reduce the width of the setting, then roll the dough through, repeating until you reach the thinnest setting (or, to make the pasta easier to work with, one setting up from the thinnest setting). You should now have a long, fine strip of pasta.
5. Lay the pasta on the floured work surface, then stamp out circles with the fluted round cutter; you should get 10-12 from the strip. Cover the circles with a clean tea towel or cling film as you work, so they don’t dry out. Take a circle and place a small teaspoon of the filling in the middle, then use a pastry brush to paint around the edge of the circle with a little of the reserved egg white. Fold over the pasta circle to make a semi-circle and seal the edges, removing any air. Bring the two ends together and squeeze to seal, making a tortellini shape. You may need to use a touch more egg white to seal the pasta. Put the completed tortellini on a baking sheet dusted with flour and leave for 5 minutes to dry a little, then cover loosely with cling film (they will keep for a few hours in the fridge like this). Repeat the rolling, cutting and filling with the other pieces of pasta.
6. To cook the tortellini, bring a large pan of water to the boil, drop in the tortellini and cook for 2-3 minutes until they rise to the surface but are still very al dente (with bite). Drain, then drizzle with a little oil.
7. For the sauce, heat a large frying pan over a medium heat. Add the butter and let it melt, then turn up the heat and add the cooked tortellini along with the sage leaves. Sizzle for 2-3 minutes until the butter starts to turn golden. Toss everything to coat and season to taste, then spoon into serving bowls and enjoy with plenty of freshly grated parmesan.