Shepherd's Pie

I used a small baking dish for this serves 2

2 large potatoes
1/4  cup  milk
2  tablespoons  unsalted butter
2  tablespoons  olive oil
1/2 kilo beef mince
1  large carrot, chopped (1 cup)
1  celery stalk, sliced (1 cup)
2  tablespoons  flour
2  cups  chicken broth
1/2  cup  frozen peas

Heat oven to 200 degrees. In a saucepan, gently heat mashed potatoes and milk, stirring occasionally, until well combined. Remove from heat and stir in butter. Set aside. Heat olive oil in a large skillet over medium-high heat. Add beef mince and cook, breaking up with a spoon, until browned, 5 to 7 minutes. Add carrot and celery, and cook 5 minutes. Sprinkle in flour, stir, then add chicken broth. Simmer 3 minutes and remove from heat. Add peas . Spoon into an ovenproof casserole and top with the mashed potatoes. Bake until the top is golden, about 40 minutes.