Preheat oven to 375 degrees F. Line baking sheets with parchment paper and set aside.

Heat butter and brown sugar in a 2-quart saucepan over medium heat, stirring frequently, until butter has melted and mixture is smooth. Stir in oats, flour, salt, egg, and vanilla.

Drop batter by the teaspoon onto prepared baking sheets, leaving about 2 inches between each cookie to allow them to spread.

Bake for about 5 minutes, until golden brown.

Allow to cool on the cookie sheet for 30 seconds and remove onto racks to cool completely. They will harden as they cool.

Microwave chocolate chips about one minute, stirring every 15 seconds to keep from burning. Once chocolate is melted and smooth, spoon it into a plastic bag. Snip the corner of the bag to make a small hole. Use this to drizzle and decorate cookies. Let set.

Store in an airtight container.