Preheat the oven to 350°F (175°C).

In a mixing bowl, whisk together the flour, baking soda, nutmeg, and salt.

In another bowl, cream the softened butter and brown sugar until light and fluffy.

Add the egg and vanilla extract to the butter mixture and mix until combined.

Gradually add the dry ingredients to the wet ingredients, mixing until just combined.

In a small bowl, mix cocoa powder and granulated sugar.

Using a cookie scoop, drop a tablespoon of dough onto the baking sheet.

Sprinkle a small amount of the cocoa mixture on top of each dough ball.

Using a toothpick or knife, swirl the cocoa mixture into the dough to create a tiger stripe pattern.

Bake in the preheated oven for 10-12 minutes, or until the edges are lightly golden.

Allow the cookies to cool on the baking sheet for a few minutes before transferring to a wire rack.