Preheat your oven to 375°F (190°C) and prepare a cookie sheet by leaving it ungreased.

Blend in a large mixing bowl the shortening, creamy peanut butter, brown sugar, milk, and vanilla using an electric mixer until everything is smooth.

Incorporate the large egg into the mixture, mixing until just combined.

Whisk together in a separate bowl the flour, cocoa powder, baking soda, and salt.

Combine the dry ingredients gradually into the wet mixture, stirring gently until fully integrated.

Scoop the dough onto your prepared cookie sheet, forming 1 to 1.5-inch balls.

Bake for 7-8 minutes or until the edges are set while the center remains soft.

Cool the cookies on the sheet for about 2 minutes, then transfer them to a wire rack to cool completely.