Add butter and chopped chocolate to a microwave safe bowl. Microwave in 10 second increments and stir until smooth and set aside.
Whisk flour, powered sugar and salt together in a small bowl.
Whisk eggs and egg yolks together in a small bowl.
Combine the flour and egg mixtures together in a bowl and stir until there are no lumps. The batter will be thick.
Spoon batter evenly into non-stick sprayed muffin pan.
Bake at 425 for 8-10 minutes.
Cool for 1 minute. Flip the pan on to a baking sheet to remove the cakes.
Serve immediately with your favorite toppings.