Preheat your oven to 180C (350F) and line a small loaf pan with parchment paper.
In a large mixing bowl, combine milk, brown sugar and sourdough starter and whisk together until it's light and foamy.
In a separate bowl add all other dry ingredients and stir through until they are all well distributed.
Now, place the dry ingredients on top of the liquid ingredients and bring together to form a thick batter (it will be a bit like a thick muffin batter).
Spoon the batter into the loaf pan you've prepared and bake in the oven for around 25 to 30 minutes at 180C (350F), or until a skewer comes out clean.
Remove from the loaf pan and allow to cool on a wire rack until cool to the touch.
Now, wrap the loaf in parchment paper and aluminum foil and place in the freezer for around 2 to 3 hours. You could leave it in the freezer for up to 3 months (perfect if you're preparing early for the festive season).
Once the loaf is frozen through, remove from the freezer and allow to sit at room temp for around 20 minutes or just until the sides aren't rock hard.
Now, use a serrated knife to slice the loaf into 2mm thin slices. Be patient, use a good bread knife and you'll be fine.
Lay the slices onto a large baking tray lined with parchment paper and bake in the oven for around 1 hour at 120C (250F) or until the sourdough gourmet crackers are dry and crispy and can be broken in half with a "snap".
Allow them to cool on the tray before enjoying with your favorite cheese!