For the cream of butternut squash soup, preheat the oven to 200C/400F/Gas 6.
Place the squash and garlic onto a baking tray, drizzle with 2 tablespoons of the olive oil and place the rosemary on top. Roast for 30-40 minutes, or until tender. Remove from the oven and set aside one quarter of the squash mixture, a clove of garlic and a sprig of rosemary.
Heat the remaining oil in a frying pan until hot, then add the onion and fry for 1-2 minutes. Add the remaining cooked squash, garlic and rosemary. Stir in the stock, bring the mixture to the boil, then reduce the heat and simmer for 3-4 minutes.
Blend the butternut squash mixture and cream in a food processor to a purée. Set aside.
For the croutons, heat the butter in a medium frying pan until hot then add the diced bread. Cook for 2-3 minutes, stirring regularly, or until golden-brown on all sides. Set aside to drain on kitchen paper.
Meanwhile, for the chicken and squash tortellini, place the flour into a large bowl and season with a little salt and freshly ground black pepper. In another bowl, whisk together the egg yolks and 3 of the whole eggs. (Whisk the remaining egg in a separate bowl and set aside.) Pour the egg mixture into the flour and stir to combine to form a firm dough.
Add the olive oil to the dough a teaspoon at a time and mix until the dough becomes pliable (you may not need all of the oil).
Turn the dough out onto a lightly floured work surface and knead until smooth and elastic. Place into a bowl, cover with clingfilm and chill in the fridge for 30 minutes.
Blend the reserved squash mixture and the chicken breast in a food processor and chill until needed.
Using a pasta machine, roll the pasta dough out according to the machine instructions, passing it through the rollers a few times on the thickest setting, then working down to the thinnest setting.
Place the rolled sheet of pasta dough onto a floured work surface and use a 7cm/2in pastry cutter to cut out circles of dough.
Place a spoonful of the reserved chicken mixture into the centre of a pasta circle. Brush the edges of the pasta with the reserved beaten egg.
Fold the pasta circle over to form a half moon shape, pressing down gently around the filling to seal. Holding both ends of the pasta, twist slightly to form a shell-like shape.
Repeat the process with the remaining pasta and filling. Place the tortellini onto a baking sheet lined with baking paper until you're ready to cook them.
To cook the tortellini, place a few tortellini at a time into a large saucepan of salted boiling water and cook for about 1-2 minutes, or until they float back to the surface, then drain the pasta.
To serve, warm the soup and ladle into each of 4 serving bowls. Place the tortellini in the centre on top of the soup. Sprinkle the croutons on top and garnish with the fresh chervil.
Type the ingredients you want to use, then click Go. For better results you can use quotation marks around phrases (e.g. "chicken breast"). Alternatively you can search by chef, programme, cuisine, diet, or dish (e.g. Lasagne).
James Martin presents, with guest chefs Matt Gillan and Ching-He Huang.