Spray 2 baking sheets with non-stick spray or line with parchment paper
In a large bowl, mix the peanut butter and eggs until smooth.
Add the cake mix and stir until well mixed. It may take a minute to come together. Alternatively, you can use a hand mixer set on low. The batter will look a bit crumbly, but it should not be dry. If there is still dry cake mix, add an extra tablespoon or two of peanut butter until you have a stiff batter.
Mix in the peanuts and chopped chocolate.
Form into balls about 1.5 inches round (about the size of a golf ball). Using a cookie scoop or small ice cream scoop will help keep them uniform. Squeeze the dough balls with your hands to help them hold together.
Place on the cookie sheet with a couple of inches room between each cookie. Then flatten the dough balls to approximately ½ inch thick.
Bake for 10-12 minutes until just set. They will still feel a bit soft in the middle but the edges should feel fully set.
Remove from baking sheet to cooling rack, allow to cool, then store in an airtight container.
Notes
Using "natural" peanut butter works best in this recipe as it has a higher oil content which helps keep the cookies moist. If you've never purchased the natural peanut butter, you'll notice it's a bit oily when you open it up. Just give it a good stir before measuring.
After testing this recipe with both the "natural" and the regular thick stuff, the natural peanut butter just worked better. But if you just don't want to bother, the regular stuff will do!
As all natural peanut butters have slightly different consistencies, you may need to add an extra tablespoon or two of peanut butter to get the dough to come together.
If you are using the regular thick peanut butter, you can add a tablespoon of vegetable oil to help the dough stay moist.
These cookies do not spread very much, if you want thinner cookies then you can flatten them more before you bake.
You may substitute chocolate chips for the chopped chocolate.
If you can’t find Devil’s food cake mix, you can use any chocolate cake mix instead.