Melt butter in a small pan over medium heat. Bring to a simmer for 3 to 5 minutes, stirring occasionally. The butter will foam and crackle. Remove the pan from heat as soon as the butter begins to brown and gives off a nutty aroma. Transfer to your mixing bowl to cool for 5 minutes.
In another large mixing bowl combine the GF flour, oats, baking soda, salt, and cinnamon.
Mix the brown sugar and brown butter, stir to combine. Add the egg and egg yolk and vanilla. Mix until smooth. Add the sugar mixture to the dry ingredients. Mix until you can no longer see any flour. Stir in the raisins. Rest the cookie dough 5 to 10 minutes to allow the flour to hydrate.
Scoop your cookie dough onto an insulated cookie sheet. Bake for 12 to 14 minutes until lightly brown. Cool on the baking sheet for 5 minutes before transferring to a wire rack to completely cool.
Video
Equipment
cookie sheet
Notes
This recipe makes 12-14 large cookies or 18-20 regular cookies.