Preheat the oven to 425 degrees. Spray a six-count muffin tin or 4 - 6 oz ramekins with non-stick spray. Dust with cocoa powder and set aside.

Place the chocolate chips and butter in a microwave safe dish and heat in 30 second increments until melted. Stir well between each interval. Allow to cool to room temp.

In a small bowl, combine the flour, powdered sugar and salt. Whisk to combine. Set aside.

In another small bowl, add the eggs and egg yolks. Whisk to combine. Set aside.

Add the dry ingredients and the egg mixture to the melted chocolate mix once it has cooled slightly. Whisk to combine well.

Pour the batter into the prepared baking dishes. Place ramekins on a baking sheet or if using a muffin tin, place directly on the middle rack.

Bake in the preheated oven for approximately 14 minutes. The tops should be set and beginning to crack. Remove from the oven and allow to cool for approximately 5 minutes.

Using a butter knife, gently run it along the edges of the cake to release anywhere that might have stuck. Place a plate or serving dish on top of the cakes, and quickly invert. Use caution and baking mitts - the pans will still be very hot.

Allow the cakes to cool slightly. Sprinkle with additional cocoa powder or powdered sugar.