Preheat oven to 360 degrees (I like the convection setting if you have it).
In a small bowl, with a fork, whisk together the butter + sugar until fully incorporated.
Mix in the egg yolk + vanilla until fully combined.
Stir in the flour, baking soda + salt until it forms a dough, then stir in desired amount of chocolate chips.
Scoop half the dough into a small baking ramekin lightly greased with coconut oil, sprinkle a few chocolate chips on top, then top with the rest of the dough. Sprinkle a little flaked sea salt on top (optional).
Bake at 360 degrees for 16ish minutes – longer if you don’t want the center to be gooey. (I personally loooove gooey.)