Frugal Pie

This is a delicious way of using up leftover meat and potatoes. I often will use any drippings or gravy instead of the broth, and I'll also make use of any leftover vegetables, popping them in at the last minute instead of cooking them again. Frugal can also mean delicious.

2 Tbsps (1oz/28gr) butter or bacon fat
1 onion, diced (TO DO: Measure the total quantity of veg and meat)
2 stalks celery, diced
2 carrots, diced
Optional 4oz mushroom, diced
1 Tbsp flour
1 cup broth (can be liquor from the roast)
¼ cup milk
1 sprig thyme, rosemary or sage
½ tsp salt
¼ tsp pepper
8 oz cold cooked red meat
1 lb potatoes (cold or already mashed, or see Step 7)

1. Sauté onion, celery, and carrots in butter until cooked through and starting to brown, about 10 minutes.
2. Meanwhile, mince the meat by hand into small but recognizable chunks.
3. Preheat the oven to 400°F.
4. Add flour to the sautée mixture, stirring well. Cook one minute, at least, or until well browned. This is important - cooking the flour in the buttered vegetables means the flour is absorbing all the liquids and fats in the pan, then cooking so that when you make the sauce, it will have carried all the lovely browning flavour with it, and it won't taste floury. 
5. Dump the broth and then the milk into the vegetable mixture and stir thoroughly. Add the thyme, salt and pepper. Cook over medium heat stirring constantly until the broth thickens and gets bubbly. 
6. Mix in the meat and put in a pie plate or casserole dish.
7. If they're not already mashed, prepare the potatoes with 3 Tbsps of milk or cream, and butter, to taste, along with a pinch of salt.
8. Layer the mashed potatoes on top of the meat mixture and put in the hot oven for 35 minutes or until the top browns.