Cream butter and sugar

• Place the softened butter in a bowl and add the brown sugar.
• Mix until well combined.

Add the wet ingredients

• Separate the egg and add the yolk to the bowl.
• Add the vanilla extract and mix in.

Add the dry ingredients

• Add the salt, baking soda, cocoa powder and flour.
• Mix only until just combined.

Fold in the chocolate chips

• Add the semi sweet chocolate chips and stir briefly to distribute.

Shape the cookies

• Split the dough in half.
• Roll each half into a ball and place on a baking tray.

Bake

• Bake at 175 °C (350 °F) until set at the edges.

Finish with flaky salt

• Sprinkle a little flaky sea salt over the warm cookies.
• Let cool slightly before serving.