Preheat oven to 350 degrees F. Line a large baking sheet with parchment.
Place brewers yeast, oats, flour and cheese in a large bowl.
In a separate small bowl, beat egg. Add egg to flour mixture and stir well. Add only enough water to make a rollable dough.
Roll out dough to 1/4-inch thickness on a lightly floured surface. Cut into desired shapes.
Bake for 30 minutes. Turn off oven and leave biscuits in there until oven is completely cool (this dehydrates them for storage).
Amount varies, but I got 2 1/2 dozen from this with a “medium” dog bone biscuit cutter.