1) Preheat the oven to 300°F. Lightly grease a couple of baking sheets, or line them with parchment.
2) Mix together the flour, oats, parsley, dried milk, and salt.
3) Add the eggs and peanut butter, stirring to combine; the mixture will be crumbly.
4) Add enough water to bring the dough together; depending on the season, you may need to add a bit more (winter), or a bit less (summer).
5) To make biscuits using a dog-bone cutter, roll the dough about 1/4" thick, and cut with a 3 1/2" cutter (or the size of your choice). Gather and re-roll the scraps, and continue to cut biscuits until you've used all the dough.
6) To make dog "cookies," drop the dough in walnut-sized balls onto the prepared baking sheets. Flatten them to about 1/4".
7) Bake the biscuits for about 40 to 60 minutes, baking the smaller cookies for a shorter amount of time. When finished, the biscuits will be dark golden brown, and will be dry and crisp all the way through.
8) Remove the biscuits from the oven, and cool right on the pans.
Yield: about 42 larger (3 1/2" dog-bone) biscuits, 60 smaller (round) biscuits.