As this is for 2 people, I’m going to make a large envelope/bag to cook everything in. Using wide tin foil, make the bag by placing 2 pieces on top of each other (about as big as 2 shoeboxes in length), folding 3 sides in and leaving 1 side open.
Preheat the oven to 220°C/425°F/gas 7.
Tear up the mixed mushrooms. Peel and slice the garlic. Mix everything together in a bowl, including the chicken. Place in the bag, with all the liquid, making sure you don’t pierce the foil.
Close up the final edge, making sure the bag is tightly sealed and secure on all sides, and carefully slide it on to a roasting tray. Place the tray on a high heat on the hob for 1 minute to get the heat going, then bake in the middle of the oven for 25 minutes.
Remove from the oven, place the bag on a big plate, take it to the table and carefully break open the foil. Feel free to vary the recipe – things like grated parsnip, smoked bacon and red wine also work well.