Preheat oven to 350 degrees.  Prepare mini muffin tins by spraying with cooking spray. 

In a medium-large saucepan, melt the coconut oil with the bittersweet chocolate over low heat, whisking occasionally until smooth and melted. Sprinkle in cocoa powder and whisk to combine. Remove the pan from heat and allow to cool for about 5 minutes.

Once cool, stir in sugar and vanilla until just combined.  One at a time, stir in the eggs.

Gently stir in the flour until halfway incorporated. Add the chocolate chips and stir just until combined.

Spoon thick batter into each mini muffin tin. 

Bake for 25 minutes, then check the brownies with a toothpick. If it is overly gooey/messy, return to the oven for 5 to 10 more minutes. 

Allow to cool completely before indulging.