Cut a piece of parchment to fit baking sheet. If using a 13x9 pan, make a sling out of the parchment in the pan and oil the ends of the pan.
After weighing out the peanuts (290 grams), crush the peanuts with a rolling pin. You don't want them whole, but you don't want them a powder like you'd get with a food processor either. I use the smallest guide on my rolling pin.
Add peanuts to a bowl.
Add oats (120 grams) to bowl
In a small saucepan, add the peanut butter (130 grams) and corn syrup (320 grams). Bring to a boil.
Once boiled, remove from heat (or turn to low) and add the chocolate chips. Stir until smooth.
Add the chocolate/peanut-butter/corn-syrup mixture to the oats and crushed peanuts and stir to combine completely. (see note)
Spread in the prepared pan/sheet and refrigerate for at least an hour.
Remove, let stand for a few minutes, then cut into bars or squares.