Preheat your oven to 375 F. Lay out two sheets of parchment (on baking tray if not using a steel or on cutting board)
If using your baking steel, make sure it is centered in the middle rack of your oven
Grate the butter and place back in fridge to chill
While butter is chilling, chop your 4 oz gouda into smaller pieces, about 1 cm square. Chop pickled serrano peppers (or herbs) into smaller pieces. Chop walnuts. Set all back into fridge
In a large bowl combine your flour, xantham gum, baking powder, baking soda, cream of tartar, and sugar. Whisk to combine
Add your grated butter and mix in gently - I use my hands for this and crumble it into the mixture
Add your cheese, walnuts and peppers and stir to combine
Now stir in gently about 200-250 g buttermilk (or half). Your mixture will start to come together. Gradually add buttermilk until the mixture is fully combine but not soaked -- it took about 500 g buttermilk for us. Your bread should be very moist but not overly wet
Transfer dough to your parchment and shape into a disk, slightly mounded toward the center, about 9 inches in diameter. (Wetting your hands helps immensely with this.) Using a sharp knife or a pastry cutter, slash an X in the dough about half way through and from edge to edge
Using a baking peel, transfer the bread and parchment into the oven and onto the baking steel
Bake at 375 F for 30 minutes. Then, increase oven temperature to 400 F and bake an additional 15. Cover with foil if bread is browning too early. You may need additional minutes if using a baking tray instead of a steel. Your inside bread temperature should be around 210 F
Remove from oven and leave to cool on baking tray for 15 minutes before removing to wire rack to cool. Slice and enjoy! We wrap ours leftovers (if there are any!) in foil and leave on the counter for a few days. You can also freeze