Using mixer with a dough hook, put all ingredients EXCEPT flour into large bowl, and mix well Add flour gradually, until dough is stiff enough to handle and to be able to roll into balls Place lower oven rack ABOVE middle rack Preheat oven to 300F Roll dough into balls and place on 2 large cookie sheets, flatten slightly with bottom of glass.
Bake for 90 minutes, turning biscuits over half way through and placing trays on alternate oven racks.
Lower oven temperature to 225 f for 1-1 1/2 hours.
Check for doneness occasionally, take one out, let cool, break apart, whole biscuit should be hard and crispy like milkbones are.
When done, remove from oven, let cool, and store in air tight container.