Scalloped potatoes - FAIL

With 3 lbs of potatoes going bad, I needed to do something fast.  I have another recipe that I used in the past, but wanted to keep experimenting. 
This recipe worked, but only after a prolonged time in the oven.  I can't even tell you how long I cooked them for.  If I had to guess, at least an hour and a half.  I'm not sure how to solve the problem, but they're ok...I guess.
Scalloped potatoes
  • 3 tbsp butter
  • 2 tbsp flour
  • 1 1/2 cup milk
  • salt and pepper
  • 5 lge potatoes, peeled, thinly sliced
  • 2 cups grated cheese
  1. Preheat oven to 350 degrees.
  2. Butter a baking dish.
  3. In a saucepan, melt 2 tablespoons butter over medium high heat.
  4. Stir in flour and cook for 1 minute, be careful not to burn.
  5. Remove saucepan from heat and whisk in milk.
  6. Return pan to heat and bring to a simmer while stirring.
  7. When sauce has thickened remove from heat, season with salt and pepper and set aside.
  8. Spread 1/3 of the white sauce in bottom of baking dish and top with half of the potatoes. And another third of the sauce. Season with salt and pepper. Continue layering ingredients, ending with the remaining cheese on top.
  9. Bake for 45 minutes or until golden and bubbly.
Stay hungry my friend!