Soak Cranberries. To start, add cranberries to a small bowl and cover with warm orange juice. Allow the cranberries to soak for 15-20 minutes, then drain as completely as possible. This will plump up the cranberries and add a subtle citrus flavor, but we don't want to add the juice or it will change the structure of the cookies.
Break Up The Oats. Place the oats in the bowl of a food processor (or the jar of a blender) and pulse a few times to break up the oats. Ideally, you want some whole, and some broken up. This just gives the cookie the best texture. Try not to pulverize the oats into flour as this will drastically change the cookie's texture.
Combine Dry Ingredients. In a medium bowl, combine gluten-free oats, gluten-free flour, cornstarch, baking powder, baking soda, and salt. Whisk to combine, then set aside.
Cream Butter & Sugar. In the bowl of a stand mixer (or a large bowl), combine softened butter, brown sugar, and granulated sugar. Cream together 2-3 minutes until smooth, fluffy, and lighter in texture. Scrape down the edges of the bowl.
Add Eggs & Vanilla. Next, add the eggs one at a time, followed by the vanilla extract. Mix to combine well, then scrape down the sides of the bowl again.
Mix In Dry Ingredients. Add the dry ingredients to the mixer and blend until just a few floury patches remain.
Add White Chocolate Chips & Cranberries. Pour in 1 cup white chocolate chips and 1 cup dried cranberries (reserve the rest of the cranberries & white chocolate chips for garnish). Mix until just blended.
Chill Dough 2 Hours. Cover the dough and refrigerate 2 hours. Do NOT skip this step, or your cookies will spread significantly more.
Preheat & Prep. When you're about 30 minutes away from baking, preheat the oven to 350 degrees F. Line two baking sheets with parchment paper so you can alternate baking sheets with each batch.
Scoop & Roll Cookie Dough. Use a large cookie scoop to scoop 3-Tablespoon balls of cookie dough. Roll the dough smooth between your hands and place 6 cookie dough balls on a prepared baking sheet.
Bake, Finish & Cool Cookies. Bake 6 cookies at a time in the preheated oven for 10-12 minutes, or until the cookies are slightly golden brown around the edges and the centers look *just* underdone. (They'll set more as they cool). Remove from the oven and gently shape with a round cookie cutter into perfect circles, if desired. Garnish with a few more white chocolate chips and dried cranberries. Let the cookies cool 1-2 minutes on the baking sheet before transferring to a wire rack to cool completely.
Repeat this process with remaining cookie dough until all cookies are baked, alternating baking sheets with each batch so you don't put cold dough on a hot cookie sheet.
Serve & Store. Enjoy once the cookies have cooled. Store in an airtight container at room temperature 2-3 days, or freeze up to 2 months.