Using ingredient baking potatoes thinly

Potato, Onion, And Rosemary Casserole

• 55 gr butter
• 7 gr rosemary snipped (fresh)
• 4 gr salt
• 2 gr pepper (freshly ground)
• 4 slices baking potatoes thinly (sliced)
• 2 slices onions thinly (sliced)