I can say that these have been tested and approved by family and friends, but my dogs approve of everything!
All people ingredients. My cousin actually tried one once, not realizing they were for the dogs. She thought they were OK, just not sweet enough. Now that I think of it, I suppose I could try a people version.
Throw all ingredients into mixer bowl. I start by throwing in the whole eggs, shell and all. The action of the mixer will break the shell into bits. My dogs don't mind having egg shell in their cookies.
Mix ingredients on low speed, using dough hook, just until thoroughly mixed - a minute or two. (This is a very dry, stiff dough; so don't mix any longer than necessary. It can be a challenge for even the toughest mixer. I have had to re-tighten the head of my KitchenAid Professional 6 every few months since I started making these cookies. )
Depending on how much of the optional moist ingredients you have added, you may need more flour. The measurements I give here are based on using 3 good sized carrots.
Divide your dough into 3 parts. Sprinkle a little flour on cutting board or counter.
Roll out the first section of dough, to the thickness that you think your dog would like. For me, that is about as thick as my finger. Keep in mind though, my dogs are not picky about the size.
Using a (dog bone shaped) cookie cutter of your choice, cut out as many cookies as you can. Place on an ungreased cookie sheet. Feel free to give your assistants (your eagerly watching dogs) bits of dough to taste for quality assurance. Repeat with the remaining two sections of dough. The cookies can be placed closely together, as they do not spread at all.
Sometimes when I'm feeling lazy I just use my dough scraper/chopper to cut the dough in strips. These are much less uniform in size, but the dogs don't mind. They end up being about the size of my fingers. Either way, dog bones or strips, I always end up with 3 pans of cookies.
Bake at 375 degrees for 18-22 minutes. Convection works well, helps to remove moisture from the cookies. Open the oven, reach in gingerly and press the nearest cookie. You want them to be kind of hard, like biscotti.
Shut off the oven but leave the cookies in until thoroughly cooled, to allow them to harden and dry out in the residual heat. I leave them in for 6-8 hours or more. Place cookies in an airtight container. (If they are not hard and dry when you store them, they may get moldy after about 5 days.)