Whisk the egg and sugar together in a large mixing bowl until pale and smooth.
Add the peanut butter, oats, bicarbonate of soda and sea salt and mix until the batter is smooth and thick.
Using the palms of your hands roll up the dough into balls of about 45g each and place on a baking sheet a couple of inches apart. Press down slightly so the top of the cookies are flat.
Bake for 6-8 minutes until the cookies are just turning golden.
Remove from the oven and leave on the baking sheet for 5 minutes to firm up before moving them to a wire rack to finish cooling.
Dip each cookie in melted chocolate and sprinkle on sea salt then leave to set.
*For a vegan cookie, replace the egg with 1 chia egg. (1 tablespoon ground chia seeds whisked into 3 tablespoons water and left to set for 5 minutes in the fridge. Use then the way you would the normal egg)*For a refined sugar-free cookie, replace the sugar with 8 pitted dates, blended to a puree. The mixture will be a little stickier before going into the oven but comes out pretty much the same cookie consistency.