Preheat your oven to 375 degrees.
Grease cookie sheets.
In large bowl, combine flour and baking powder. Use another bowl and combine the peanut butter and milk.
Add the milk and peanut butter mixture to the dry ingredients and mix well.
On floured surface, turn out the knead. Roll out to 1/4" thick. Cut out using cookie cutters.
Place on baking sheets and bake for about 20 minutes or until lightly browned. Place on racks to cool then store in airtight containers.
Storing Dog Treats
In general you should store dog treats the same way you would homemade people cookies. That being said, there are two main variables that determine storage time - the amount and type of fat in the recipe and your local weather conditions. If your recipe uses fats such as butter, or meat bits or juices then it will be more prone to rancidity than a recipe that uses some vegetable oil or shortening. Your treats may mold or spoil much faster in humid or very hot climates.
Refrigeration and Freezing - Refrigeration will prolong the life of more fragile dog treats. Make sure to store in a tightly sealed container or zip lock bag. You can also freeze most treats in zip lock freezer bags. Allow to thaw completely before use.