Easy Au Gratin Potatoes on Top of the Stove

0 Bring salted water to boil in a large pot.
1 Turn down to simmer and add the sliced potatoes.
2 Simmer until they are tender.
3 Drain and set aside.
4 Meanwhile melt the butter in a heavy frying pan.
5 Add the onions and saute until they are tender.
6 Remove from pan and set aside.
7 Add 1 tablespoon more of the butter to the pan.
8 Melt it and then add the flour, whisking constantly.
9 Cook on  low, stirring constantly for 2 minutes.
10 Add the salt, garlic powder, and evaporated milk, whisking constantly until no lumps remain.
11 Add the dried onions.
12 Simmer, stirring constantly, until the mixture begins to thicken.
13 Add the 2 cups of cheese and stir until smooth and creamy.
14 Remove from heat.
15 Add a layer of potatoes to the casserole dish.
16 Cover with a layer of the cooked onions, about 1/2 cup of the sauce, and about 1/4 cup of the grated cheese.
17 Repeat, ending with a layer of grated cheese.
18 Broil the top of the casserole with a kitchen torch if desired.
19 Cover with aluminum foil and set aside until ready to serve.