In a large frying pan, dry-fry the bacon over a medium heat for 3 mins until the fat is released and the bacon is golden. Transfer the bacon to a small bowl, leaving the fat in the pan. Add the chicken and brown for 4 mins each side.
Push the chicken to one side of the pan and tip in the garlic and spring onions, cooking for about 30 secs, just until the spring onion stalks are bright green. Pour in the chicken stock, return the bacon to the pan, cover and simmer for 15 mins.
Increase heat under the pan. Tip the peas and lettuce into the sauce and cook for 4 mins, covered, until the peas are tender and the lettuce has just wilted. Check chicken is cooked through. Stir in the crème fraîche just before serving.
