Makes about 10 cookies. Can use crunchy or smooth peanut butter.
Preheat the oven to 175C (350F) and line a tray with baking parchment.
In a large bowl, combine 66 g (⅓ c) brown sugar, 66 g (⅓ c) granulated sugar, and 1 t baking soda. Add and blend in a pinch of salt if using unsalted peanut butter. Next, add 1 large egg and 250 g peanut butter, and then mix thoroughly to combine.
Use two spoons to maneuver walnut-sized balls of dough on to the tray, leaving ample space between each cookie since they will rise and spread. Flatten the balls slightly with a fork, creating a cross-hatch pattern.
Bake in a 175C (350F) oven for 8–10 minutes. Allow them to cool on the tray for at least 5 minutes, then move to a rack to cool further. They will be very soft to the touch fresh from the oven and firm up as they cool.