sharp cheddar scalloped potatoes

Ingredients For sharp cheddar scalloped potatoes

• 1/4 c

  (1/2 stick) butter
• 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
• 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 sm

  onions, finely chopped