Au Gratin Potatoes

4 russet potatoes, sliced into 1/4 inch slices
1 onion chopped
salt and pepper to taste
3 TBSP butter
3 TBSP flour
1/2 tsp salt
2 cups milk
1 1/2 cups shredded cheddar cheese
jalepeno chopped (optional)

Preheat oven to 400 degrees. Butter a 9x13 pan.

Layer 1/2 of the potatoes into bottom of pan. Top with the onion and add the remaining potatoes. Season with salt and pepper to taste.

In a medium saucepan, melt butter over medium heat. Mix in the flour and salt and stir constantly with a whisk for 1 minute. Stir in milk. Cook until mixture has thickened. Stir cheese all at once, and continue stirring until melted (about 30-60 seconds). Pour cheese over the potatoes, and cover with foil.

Bake 1 1/2 hours in oven.