Preheat the oven to 325F and grease a small ramekin (4 ounce capacity)
In a small bowl, whisk together the butter and sweetener. Stir in the egg yolk and vanilla.
Stir in the almond flour, baking soda, and salt until well combined and then stir in most of the chocolate chips, saving a few to press into the top of the cookie.
Scrape the batter into the prepared ramekin and press remaining chocolate chips into the top. Bake 15 to 20 minutes, or until golden brown on the edges but the middle is still a little soft to the touch.
Remove and let cool for a few minutes before eating. Top with your favourite low carb vanilla ice cream for a serious treat!