Jamie Oliver chicken pie, peas and carrot smash.

Name: Jamie Oliver chicken pie, peas and carrot smash.
Cuisine: European, British
Ingredients: 4x 180g chicken breasts; Knob of butter; Bunch of spring onions; 150g button mushrooms; 1 heaped Tbsp plain flour; 2 Tsps English mustard; 1 heaped Tbsp creme fraiche; 300mls chicken stock; Few sprigs fresh thyme; 1/3 nutmeg for grating; 1 sheet of pre rolled puff pastry; 1 egg; 600g carrots; Few sprigs fresh thyme; 2 little gem lettuces; Knob of butter; 1 Tbsp plain flour; 300mls chicken stock; Few sprigs fresh mint; 480g frozen peas; 1/2 lemon; Olive oil; Salt and pepper