Preheat your oven to 325°F. Grease and line an 8-inch x 8-inch (for thicker bars) or 9-inch x 9-inch (for thinner bars) baking pan, and set it aside.
Make the blondies.
In a large bowl, place the flour blend, xanthan gum, cornstarch, salt, and baking soda, and whisk to combine well. Set the mixture aside.
In a small, heavy-bottom saucepan, place the butter and granulated sugar. Place over medium-low heat and bring to a very light simmer, whisking frequently. The butter and sugar should be melted and smooth.
Remove the pan from the heat, and add the brown sugar. Whisk to combine and to melt the brown sugar until smooth. Set the saucepan aside to cool briefly.
In a large mixing bowl, place the eggs and vanilla and beat with a handheld mixer or whisk with a large balloon whisk until foamy.
While whisking or beating constantly, add the butter and sugars mixture. Continue whisking or beating until very smooth.
Add the dry ingredients, and mix by hand until well-combined. The batter will be very sticky, and very soft and pourable.
Add most of the chips (about 5 of the 6 ounces), and mix until evenly distributed throughout the batter.
Pour the batter into the prepared baking pan, and shake and spread it into an even layer. Bang the pan flat on the countertop to break any large air bubbles in the batter.
Sprinkle the remaining chips evenly on top of the batter. Bang the pan again a few times to help the chips adhere.
Place the pan in the center of the preheated oven and bake until a toothpick inserted in the center comes out nearly clean, with just a few moist crumbs attached (about 40 minutes for the 9-inch x 9-inch pan, and about 50 minutes for the 8-inch x 8-inch pan).
Remove the pan from the oven, place the pan on a wire rack and allow the bars to cool in the pan until stable enough to move without cracking (at least 20 minutes).
Remove the bars from the pan, place on the wire rack and allow to cool completely.
For cleaner slices, place the cooled pan of brownies in the refrigerator for 30 minutes. Slice into 9 equal squares.
Video
Notes
For the chips You can use any sort of stable mix-ins that you like. If you’re using white chocolate and butterscotch chips, like I do mostly, read labels carefully to ensure that everything you’re using is safly gluten free.If you like nuts in your blondies, I recommend replacing half of the chips with chopped raw pecans. You can also use walnuts, or any other nut that is tender when raw.