- First make the tarragon butter. Mix the butter with a quarter teaspoon of salt, some freshly ground black pepper, the tarragon and the garlic. Spoon the butter on to a sheet of clingfilm, greaseproof paper or non-stick baking paper and shape into a 3cm-wide roll. Wrap up tightly and chill until firm.
- Preheat the oven to 200°C/Gas 6. Flip your chicken onto its breast and, using poultry shears or kitchen scissors, cut along either side of the backbone. Open the chicken out, turn it breast side up again, then press your hand firmly along the breast bone until it lies flat. Carefully push your fingers between the skin and the flesh, leaving the skin attached only at the end of each leg. Spoon small amounts of the butter evenly under the skin, pushing it into place from the outside. Secure the skin at the neck opening in place with a small, fine trussing skewer.
- Scatter the flattened garlic cloves down the centre of a lightly oiled roasting tin and place the chicken on top, skin side up. Brush with oil, season and roast for about 35 to 40 minutes, or until the juices run clear when the thickest part of the meat is pierced with a skewer. Lift the chicken onto a board, wrap it loosely in foil and leave it to rest for about 15 to 20 minutes until it is just cool enough to handle.
- Meanwhile, put the potatoes into a pan of water, bring to the boil and cook until tender. Put the eggs in a pan of simmering water and cook for 8 minutes. Mix the salad cream ingredients together.
- Drain the potatoes and, when cool enough to handle, cut in half. Peel the eggs and cut into quarters. Pull the chicken meat away from the bones in large chunks. Scatter the lettuce leaves over a large plate and arrange the warm chicken, potatoes, eggs, beetroot, cucumber, tomatoes, spring onions and radishes in among the leaves. Drizzle over some of the salad cream and serve with the remainder in a separate bowl.
Find more recipes in Yeo Valley's Great British Farmhouse cookbook