Preheat oven to 375F and line a cookie sheet with parchment paper.
In a large bowl using an electric mixer, stir together pumpkin, peanut butter, and egg yolk until completely combined.
In a separate bowl, whisk together flours and baking powder.
Gradually add flour mixture to pumpkin mixture until completely combined (dough will be quite dry).
Transfer dough to a lightly floured surface and roll out to approximately ¼" thickness.
Use cookie cutters to cut shapes out of dough and transfer cutout cookies to prepared cookie sheet, placing at least 1" apart.
Re-combine any dough scraps and re-roll and then cut out to use all of your dough.
Bake cookies on 375F for 20 minutes for small cookies and 25 minutes for large cookies.
Allow to cool completely before sharing with your pet.
Keep uneaten cookies in an airtight container for up to two weeks.
Notes
*Please double check the ingredients to ensure that the peanut butter does not contain xylitol, which can be toxic to dogs. Most peanut butters do not contain this, but always double-check the ingredient list just to be safe. Just as a precaution, also please be aware of any allergies your dog may have before feeding, it can't hurt to check with a vet first!