Instructions

Preheat oven to 350F. Line a baking sheet with parchment paper or a silicon baking mat.
In a large bowl, whisk together the egg, brown sugar, peanut butter, oil, and vanilla.
In a separate bowl, mix together the flour, cocoa powder (you may want to sift the cocoa), baking powder, salt, nuts, and chocolate chips.
Add the dry mixture to the wet by gently folding with a spatula, starting with incorporating only half the dry mixture, and then the rest. The mixture will be quite thick.
Form 9-10 balls of dough (around 1.5 tbsp per ball) and place on the lined baking sheet. A large ice cream scoop works well for this. Then gently press down on each cookie with a spatula (the dough will be sticky/oily, so using something like a silicon spatula will prevent it from sticking to your hands too much). Top each cookie with 2-3 mini marshmallows.
Bake for around 10-12 minutes. Let cool completely, and store in an airtight container.

Notes

For Vegan: Replace egg with 3 tbsp aquafaba (the liquid from a chickpea can). I’ve tried this substitution and it works great in this recipe! Instead of the aquafaba, you could also try using an extra 1/4-1/2 tsp baking powder and/or adding one flax egg (1 tbsp ground flaxseed + 2.5 tbsp water, let sit for 5 minutes before mixing with other ingredients). I have only tried these with the aquafaba substitution. Also, use vegan marshmallows and chocolate chips.

For Gluten Free: Use gluten free 1:1 flour, and ensure chocolate chips are gluten free.

For Nut Free: Replace peanut butter with sunflower seed butter or tahini, and replace nuts with chopped up pretzels, graham crackers (or just omit the nuts!).