Homemade Au Gratin Potatoes

I made this last week, it was the first time I made it from scratch, and I was surprised at how easy it was. Besides cutting up the potatoes, it was very basic and fast. I used a mandolin to cut the potatoes. I think you could do it by hand, but this way is so much faster and easier. We had it with grilled pork chops, but really the possible combinations are endless.

Here's the recipe:
2 tbsp. butter
1 small onion, chopped
1 tbsp. flour
1/2 tsp. salt
1/4 tsp. pepper
2 c milk
2 c shredded sharp cheddar cheese
6 medium potatoes, peeled and thinly sliced
1/4 c dry bread crumbs

--Melt butter over medium heat. Cook onion in butter about 2 minutes. Stir in flour, salt and pepper. Cook, stirring constantly, until bubbly, remove from heat.
--Stir in milk. Heat to boiling, stirring constantly. Boil and stir 1 minute; remove from heat. Stir in 1 1/2 cups of the cheese until melted.
--Spread potatoes in casserole. Pour cheese sauce over potatoes. Bake uncovered 1 hour.
--In small bowl, mix remaining 1/2 cup cheese and break crumbs; sprinkle over potatoes. Bake uncovered 15-20 minutes or until top is brown and bubbly and potatoes are tender. (This was not quite long enough to get the potatoes soft enough. Cover with foil and cook another 10 minutes).