Spring Chicken Cottage Pie

Name: Spring Chicken Cottage Pie
Ingredients: 700 g chicken mince; 1 large carrot, peeled and finely chopped; 1 leek, thinly sliced; 2 shallots, finely chopped; 2 Tbsp tarragon, finely chopped; 4 Heaped tbsp half-fat crème fraiche; 1 Tbsp olive oil; Zest of 1 lemon; Squeeze of lemon juice; Salt and pepper; 800 g potato, peeled and roughly chopped; 4 spring onions, finely sliced; A splash of milk