Preheat oven to 350 degrees. Prepare a baking pan with a silicon baking mat or parchment paper.
Combine the oats, coconut, gluten-free flour, salt, walnuts, and cranberries in a medium bowl. Set aside. In a separate bowl, stir together mashed banana, honey, vanilla, and coconut oil. Add to dry ingredients and stir until completely combined.
Line the lid of a quart size mason jar with saran wrap to use as a cookie mold. Fill with the cookie dough and flip over onto the prepared baking sheet. Lift off the mason jar lid, then the saran wrap. Repeat steps with remaining cookie dough to make 6 cookies.
Bake for 20-25 minutes, or until edges are golden brown. If you aren’t using a silicon baking mat, keep an eye on the bottom of the cookies. Cool on baking sheet. Store loosely covered.