Place the bacon fat and sugars in a mixing bowl and mix on high speed for several minutes until pale in color and fluffy in texture. This step is crucial, do not skip it. Beating the bacon fat and sugar to the right consistency will help ensure a well-risen and tender finished cookie.
Add the peanut butter and beat for a few more seconds until incorporated. Next add the eggs and beat another few seconds until combined.
In a separate bowl, whisk together the flour, baking soda, baking powder and salt. Add the dry ingredients to the wet mixture and mix until thoroughly incorporated.
Using a small scoop, form the dough into 1-inch balls and place them on a non-stick cookie sheet, Bake for 9 minutes.
Let the cookies cool on the cookie sheet completely. Store in an airtight container.
After I cook bacon I allow the rendered fat to cool in the pan and store in an airtight jar in the refrigerator. I keep adding to it until I have enough to cook or bake with.