In a large bowl or the bowl of a standing mixer, cream butter and sugar (both kinds). You should end up with a white and fluffy paste.

Mix in the egg and egg yolk and vanilla extract.

In another mixing bowl, stir together the dry ingredients - gluten free flour, xanthan gum, baking soda, baking powder and salt. Add in batches to the wet ingredients, mixing well in one bowl until everything is fully incorporated.

Add chocolate chips and half the chopped white chocolate. Mix well. Dough will be thick.

Refrigerate cookie dough for 1 hour, or until the next day.

When ready to bake, preheat the oven to 320 F. Line a baking sheet with parchment paper or a reusable silicone mat.

Using a medium cookie scoop, shape the cookie dough into even balls. Arrange balls on 2 inches apart on the prepared baking sheet. Refrigerate for at least 30 minutes.

Transfer to a pre-heated oven set to 320 F for 13-16 minutes (13 will give you very fudgy cookies, while 16 will give you crispier cookies).

PRO TIP: Halfway through the bake, tap the sheet 5-7 times to flatten the cookies. Run a cookie cutter larger than your cookies around the edges, nudging the shape to be a more uniform circle with crisp edges (see my video for how to do this!). Finally, flatten the remaining white chocolate pieces into the top of the cookies.

Return cookies to the oven to finish baking. Tap them again when they come out.