In a large bowl, combine the quick oats, brown sugar, granulated sugar, flour, and salt. Stir well to evenly distribute the sugars and coat the oats.

Use the back of a spoon to make a well in the center of the dry mixture.

Pour the melted (and cooled) butter, beaten egg, and vanilla extract into the well.

Stir from the center outward until a soft, cohesive batter forms. It will look loose at first but thickens as it rests.

Let the batter sit for a minimum of 30 minutes covered at room temperature, some flours may benefit from a longer rest - I usually do an hour or so to be sure. This gives the oats time to hydrate, helping the cookies spread evenly during baking.

Preheat your oven to 350°F (175°C). Line two baking sheets with parchment paper or silicone baking mats.*

Drop ½ teaspoonful portions of batter onto your lined baking sheets, spacing each mound at least 2½ inches apart.

These cookies spread significantly and will bake into very thin, lacy discs.

Bake for 5-7 minutes, watching closely. They are done when they are golden brown and the centers appear bubbly.

Allow the cookies to cool completely on the baking sheet -they will be too delicate to move while hot. Once cooled, they crisp up beautifully.

*Parchment paper will tend to yield slightly crisper more golden cookies than the Silpat and is my preference.