- Raise the rack in your oven. You may need to run the broiler briefly to brown the potatoes. 
- Pre-heat your oven to 350. 
- Boil potatoes in well salted water. 
- Warm the stew in a saucepan. Add a bit of chicken stock if it seems low on liquid. You want a bit of sauce along with the meat. 
- Using a fork, mash the butter and flour together. You want this well mixed. 
- Off heat, add the butter/flour mixture to the stew and stir to combine. 
- Mash potatoes with 1 Tbsp of butter and the warmed milk. 
- Add the egg and cheese and mix. 
- Put the thickened stew in an ovenproof dish and top with mashed potato mixture. 
- Smooth the potatoes then drag a fork through the potatoes to create some texture. Or you could just use a spatula to rough up the top like I did. 
- Bake for about 20 minutes. Place a cookie sheet below to catch any drips. 
- If you want to brown the top, broil briefly but watch carefully to make sure you don't over brown the potatoes. 
- Let stand about 15 minutes and serve.