Preheat your oven to 375 F. Line a large baking sheet with 2 sheets of parchment
Grate the butter and place back in fridge to chill
While butter is chilling, chop your 4 oz cheddar into smaller pieces, about 1 cm square. Chop chives. 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 chives 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 480 g buttermilk for us but anywhere up to or near 500 g seems to work as well. A wetter bread simply will not rise as well but will taste great
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
Bake at 375 F for 30 minutes. Then, increase oven temperature to 400 F and bake an additional 15. Cover with foil and bake an additional 5 minutes or until about 200 F in the center or browned throughout. Every oven is different -- you may need an additional 5-10 minutes
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