Step 1

Melt the butter in a small bowl in the microwave, using 8s increments

Step 2

Add the white and brown sugar, and whisk for 1-2 minutes

Step 3

Add half of an egg yolk and whisk again for 30-60 seconds. The mixture should look very smooth at this point

Step 4

Sift in the flour, baking soda and salt, and use a small rubber spatula or spoon to very gently fold until the flour is almost combined (but not fully)

Step 5

Add the chopped chocolate and continue to gently fold only until no more streaks of flour are visible. You should not overmix after adding the dry ingredients and chocolate!

Step 6

The batter will be a bit runny at this point - don't worry and chuck into the freezer for 10-15 minutes

Step 7

In the meanwhile, pre-heat the oven to 375F and line a small baking sheet with parchment paper

Step 8

Once the dough is chilled, gently form it into a ball, and place onto the baking sheet

Step 9

Bake for just 10-12 minutes until the cookie is firm around the edges but a bit soft in the middle

Step 10

Remove from the oven and let cool for 10-15 minutes before eating!