Preheat the Oven: Start by preheating your oven to 425°F (220°C) and greasing four ramekins with butter. This will ensure your cakes slide right out after baking.
Melt the Butter and Chocolate: In a microwave-safe bowl, melt the butter and chocolate chips together in 30-second increments, stirring in between until completely smooth.
Mix in the Sugar: Once melted, stir in the powdered sugar until well combined. This will give your cake that oh-so-sweet taste!
Add the Eggs and Vanilla: Add in the eggs, egg yolks, and vanilla extract. Stir until the mixture is smooth and glossy.
Fold in the Flour: Gently fold in the flour and a pinch of salt until just combined. Be careful not to over-mix!
Divide the Batter: Evenly distribute the batter among the prepared ramekins, filling them about 3/4 full.
Bake: Place the ramekins in the preheated oven and bake for 12-14 minutes, or until the edges are firm but the center is still soft and jiggly.
Cool and Serve: Allow them to cool for one minute. Then, carefully invert each ramekin onto a plate. Serve immediately with a scoop of ice cream or whipped cream if desired.