Sharp Cheddar Scalloped Potatoes

(Courtesy of Taste of Home)

Ingredients:
1/4 c. butter, cubed
1/3 c. all-purpose flour
3/4 tsp. salt
1/2 tsp. ground mustard
1/2 tsp. white pepper
2 c. half-and-half cream
1 1/2 c. (6 oz.) shredded sharp white cheddar cheese
1 1/2 c. (6 oz.) shredded sharp cheddar cheese
6 c. thinly sliced peeled Yukon Gold potatoes (about 2 lbs.) 
2 small onions, finely chopped

Directions:
Preheat oven to 350 degrees.  In a large saucepan, heat butter over medium heat.  Stir in flour, salt, mustard and pepper until blended; cook and stir 2-3 minutes or until lightly browned.  Gradually whisk in cream.  Bring to a boil, stirring constantly; cook and stir 1-2 minutes or until thickened.  Remove from heat.

In a small bowl, combine cheeses.  Layer a third of the potatoes, a third of the onions and 3/4 c. cheese mixture in a greased 3 quart baking dish.  Repeat layers twice.  Pour sauce mixture over top; sprinkle with remaining cheese.

Bake, covered, 45- minutes.  Uncover; bake 25-30 minutes longer or until potatoes are tender and top is lightly browned.