Spoon large teaspoons of peanut butter onto a lined tray and put in the freezer for 30 minutes or until frozen.
Meanwhile. In a large bowl place room temperature butter, vanilla brown sugar, and caster sugar and mix with a spatula until creamy. Add egg and combine.
In a medium-size bowl, sift together: flour, cocoa, salt, and baking soda and mix until well combined.
Incorporate flour mix two times into butter mix: don’t over mix the batter if you want to get soft cookies!
Put cookie dough in the refrigerator for about 30 minutes (you can leave it in the fridge for 24 hours or in the freezer for 1 month).
Shape cookie dough into balls, flatten the ball, place in the center one frozen peanut butter scoop, fold the cookie dough edges to seal well, and roll into a ball.
Place 6 cookie balls onto a lined baking sheet and bake in preheated oven (upper and lower heat) at 180°-350°F for 9 – 13 minutes. Remove from the oven immediately, when still hot.
Wait about 10 minutes to remove cookies from the baking sheet and cool them down completely on a wire rack.