Slow cooked au gratin potatoes

Slow Cooked Au Gratin Potatoes
5 – 6 medium potatoes, peeled and sliced ¼ “ thick
½ cup onion, minced
3 Tbl. butter
3 Tbl. flour
2 cups milk
4 oz. smoked gouda, shredded
4 oz. sharp cheddar, shredded
3 Tbl. parmesan cheese, grated
salt and pepper
cooking spray
Coat the interior of the slow cooker crock with cooking spray.  Evenly layer the potatoes with the onions.  Sprinkle each layer with a pinch of salt and pepper.
In a medium sauce pan, melt the butter over medium heat.  Add the flour and cook for 1 minute, until the butter is completely absorbed.  Slowly add the milk and heat for 3 – 5 minutes, or until slightly thickened.  Do not allow the sauce to boil.  Remove from heat and add all three cheeses at once.  Stir until the cheeses have melted.
Pour the cheese sauce over the potatoes.  Cook the mixture on high for 2 – 3 hours and then reduce the temperature to low. Cook for an additional hour, or until the potatoes have completely softened.  Total cook time in the slow cooker will roughly be 4 – 4 1/2 hours. There should be no need to stir during cooking.  Serves about 4 – 6 people as a side.  The recipe can be easily doubled.