Named for their wholesome and earthy ingredients like rolled oats and flax seeds, these are nonetheless huge, gooey, and full of chocolate. My Sunday school teacher in high school made them every week. —HMMessinger
In the bowl of a stand mixer fitted with a paddle attachment, cream together the butter, salt, and sugars until well-incorporated and airy.
Add in egg and vanilla and beat until the mix resembles a smooth buttercream.
Add the flour, baking soda, and baking powder and mix on a low speed until just combined.
Using your hands, fold in oats, walnuts, flax seeds, and chocolate.
Roll into 3-ounce balls, then chill dough for at least 30 minutes. The longer you chill it, the less it will spread during cooking. I chilled mine for about 8 hours.
Preheat oven to 350° F. Bake for 15 to 16 minutes, then let them sit on the pan for 10 minutes before transferring to a cooling rack. They won't look done when you pull them out of the oven, but the residual heat from the pan will give them just the right amount of gooey-ness as they rest.