Flourless oatmeal lace cookies - chinese grandma

Ingredients

• 2 1/2 cups rolled oats (old-fashioned or quick-cook, not instant)
• 1/2 cup (1 stick) butter, melted
• 1 cup firmly packed brown sugar
• 1 egg, lightly beaten
• 1/4 teaspoon salt (if using unsalted butter)