• Preheat your oven to 350°F. Line rimmed baking sheets with unbleached parchment paper and set them aside.

Make the dough.

• In a large bowl, place the flour, xanthan gum, cornstarch, dry milk, baking soda, baking powder and bouillon powder, and whisk to combine well. Create a well in the center of the dry ingredients and add the butter and 3 1/2 ounces (7 tablespoons) of the milk, mixing to combine after each addition. Add more milk by the half-teaspoonful as necessary to hold the dough together when squeezed with clean hands.

Shape the dough.

• Turn out the dough onto a lightly floured surface and roll out into an even layer about 1/4-inch thick, sprinkling very lightly with more flour as necessary to prevent sticking. The dough should roll out easily and will become smoother as you roll it out. Cut into 2 1/2-inch long rectangles using a scalloped cookie cutter or a pizza or pastry wheel. Pierce the rectangles randomly on top with a toothpick or wooden skewer. Place about 1 inch apart on the prepared baking sheets. Gather and reroll the scraps to cut out more crackers until you’ve used up the dough.

Bake the crackers.

• Place the baking sheets, one at a time, in the center of the preheated oven and bake for 12 minutes, or until the crackers are very light golden brown all over. Allow to cool for 10 minutes on the baking sheets before transferring to a wire rack to cool completely.

Storage.

• The crackers can be stored in a sealed glass container at room temperature and should maintain their texture for at least 5 days.