For the brodo, lightly oil the chicken wings, bacon and venison bones. Tip into a flameproof roasting tin and roast at 190C/170C fan/gas 5 for 40 mins, tossing once, until fully cooked through and evenly dark golden brown. Strain the bones through a colander to remove any rendered fat, reserving it. Put the bones in a bowl and set aside.
In the same roasting tin, add a splash of the reserved fat, the celery, shallots and carrots. Peel the garlic and add this along with the thyme, half the sage, the peppercorns and juniper berries. Roast for 30-35 mins, then scrape into the bowl with the bones.
Pour the wine into the roasting tin and set over a low heat, using a wooden spoon to scrape up any browned bits. Bring to the boil, then reduce the heat and simmer for 5 mins or until the wine has reduced by half. Scrape into a large pan or flameproof casserole along with the bones, roasted veg and chicken stock. Season. Set over a medium heat and bring to the boil, then reduce the heat and simmer for 3-4 hrs, skimming off any fat that rises to the surface.
Meanwhile, make the pasta dough. Tip the flour into a food processor. Combine the egg yolks, whole eggs and oil in a jug, and pour this into the processor in a slow, steady stream with the motor running until a soft dough forms – it will resemble the texture of wet couscous.
Turn the dough out onto a clean worksurface and knead until the dough is smooth and springy. Wrap and chill for 30 mins. For the filling, combine all the ingredients in a bowl, seasoning well. Cook a small pinch of the filling mixture in a hot pan until cooked through, then taste for seasoning and adjust if needed.
Cut the dough into four pieces and roll out on a lightly floured worksurface with a pasta roller to a 2mm thickness. Using a 7cm biscuit cutter, stamp out as many discs as you can. Spoon a teaspoon of the filling into the centre of each disc, and fold the dough over to form a semi-circle, ensuring there are no air bubbles. Seal the pasta by gently pressing the edges together. If the dough is not sealing, lightly brush with a little cold water. With your thumb and index finger, take the pointed ends of the semi-circle, fold the tortellini in half and press the two points together to seal. Cover the prepared tortellini with a damp towel to prevent them drying out while you make the rest.
Pass the brodo through a colander, then a double layer of muslin over the rest of the sage and leave to infuse for 10 mins. Transfer the brodo to a pan and warm over a low heat.
Bring a large pan of salted water to the boil. Cook the tortellini in batches for 4-5 mins or until they float to the top. Drain and divide between bowls. Pour over the brodo to serve.
